From 2020 to 2022, an organized criminal group stole and then resold catalytic converters through the United States. The regional theft rings sent their stolen catalytic converters to DG Auto Parts in Freehold, New Jersey, who removed the precious metals from them and ground them into dust. The precious metals were then sold to Dowa Metals and Mining America for refining, after which they were sent to Japan; these sales are believed to have generated approximately $545 million in revenue for DG Auto Parts.

The investigation that led to the discovery of the interstate theft ring was prompted by a wave of catalytic converter thefts in the Oklahoma area in late 2020 and early 2021, with similar rises across the United States. On May 2, 2021, police became aware of Tyler Curtis, the owner of Curtis Cores in Broken Arrow, Oklahoma, when he was involved in a traffic stop where (among other illicit things) 128 catalytic converters were found in the bed of his pickup truck; all had jagged edges, suggesting they had been stolen. By September, a team of investigators had linked Curtis Cores with DG Auto Parts, which was owned by Navin and Tinu Khanna.

The investigation expanded between then and the third quarter of 2022, by which time it was nicknamed Operation Heavy Metal, included over 70 local and federal agencies and linked independent investigations into regional theft rings in California, Colorado, Connecticut, Minnesota, New York and Virginia. On November 2, police executed simultaneous search warrants across the US on over 32 sites, resulting in 21 arrests in 5 states. The dismantling of the interstate theft ring was described as the first national takedown of a catalytic converter theft ring by the Department of Justice.

Following the dismantling of the interstate theft ring, the theft of catalytic converters dropped dramatically. According to the National Insurance Crime Bureau, over 5,000 catalytic converter thefts were reported per month in 2022. In the first nine months of 2023, there were 2,675 catalytic converter thefts reported per month.

A catalytic converter is a typically oblong-shaped vehicle emissions control device that makes up part of an automobile's exhaust system. The catalytic converter accelerates a chemical reaction using heat and precious metals contained within the device, such as platinum, rhodium, and palladium (PRP), to transform toxic engine exhaust gases into less-toxic pollutants and other non-polluting gases. Catalytic converters became mandatory in American automobiles following the Clean Air Act of 1975, but are easy to surreptitiously remove from vehicles.

According to a 2023 report by the National Insurance Crime Bureau (NICB), metal recyclers will often "pay between $50 to $250 for a catalytic converter and up to $800 for one that was removed from a hybrid vehicle." The devices are typically much more valuable to the theft's victim: "it can cost between $1,000 and $3,500 or more to replace a catalytic converter that is stolen, depending on the type of vehicle." In 2022, catalytic converter thefts cost victims over $382,000,000.

From 2001 to 2021, the price of PRP rose dramatically: platinum rose from $530 per ounce to about $1100 ($912.00 to $1,237, adjusted for inflation). This led to an epidemic of thefts targeting the device for sale to scrap dealers. In a 2021 report, the NICB stated that "in 2018, there were 1,298 catalytic converter thefts reported. In 2019, 3,389 thefts were reported. In 2020, reported catalytic converter thefts jumped massively to 14,433, with December leading the way with 2,347 thefts, or roughly 16 percent of the yearly total – in just one month." According to records from Carfax, which examined service records that listed 'stolen' as the reason for the catalytic converter replacement, it is estimated that 153,000 catalytic converters were stolen in America in 2022.

Initially, the operation of the theft scheme appeared a continuation of this baseline trend. In the 2023 report, the NCIB stated that "based on insurance claims, thefts of catalytic converters increased significantly from 2020 through 2022". In addition, there were 16,660 insurance claims for catalytic converter thefts in 2020, a number that had increased to 64,701 by 2022. The report also stated that the highest rate for catalytic converter theft claims between 2020 and 2022 was California, with 24,102 thefts reported to insurers. In 2022 alone, an average of 1,600 catalytic converters were reported stolen each month in California.

Dowa Holdings is a precious metals refiner that began in 1884 as a mining operation in the town of Kosaka, Akita Prefecture. The company specialized in mining kuroko ore, a rare black volcanic deposit found only in Japan and primarily in Akita Prefecture in the Hokuroku Basin. Dowa expanded its domestic mining operations during the early 20th century and began exploring international opportunities for expansion in the 1940s. By 1990 Kosaka Mine had closed and by 1994 Dowa's domestic operations in Japan were suspended "due to economic changes and the depletion of ore".

In 2015, Dowa Holdings established Dowa Metals & Mining America, starting their operations at a refinery in Burlington, New Jersey, some time after. After Dowa evaluated the PRP dust that it received, it would pay its suppliers and refine the dust into chunks in their refinery. It is unknown as to whether Dowa Metals & Mining America performed any form of vetting on DG Auto Parts. The chunks would then be shipped to Tanaka Precious Metals in Akita, where they would be prepared for sale. Between 2018 and 2022, Tanaka Precious Metals' annual revenue increased by approximately 20% to $288 million.

Navin and his brother, Tinu Khanna, were first-generation immigrants from India. Their older brothers owned and operated a wrecking yard and, after working there for a few years, Navin and Tinu began their own business ventures. In 2016 they began a rubber disposal business, in 2018 they began a recycling business and in 2019 they also started a company in the auto wrecking industry under the name DG Auto Wreckers. According to an interview performed by Navin with ACE Finance, none of their prior endeavors succeeded until DG Auto Wreckers; this success was due to finding Dowa Metals & Mining America.

A subpoena into the brothers' bank records corroborated the interview: between March 2021 and April 2022, a total of $224,000,000 was transferred by Dowa into a single account used by DG Auto Parts. A further $175,000,000 was discovered on another account.

DG Auto Wreckers traded in used car parts, including catalytic converters. Initially, the business remained small, with sellers bringing in small loads from across New Jersey. However, when the COVID-19 pandemic began, the prices of PRP metals rose drastically. In December 2019, rhodium cost $6,000 per ounce and by March 2021, the price rose to $21,000 per ounce, with platinum and palladium seeing similar rises.

The brothers incorporated the business as DG Auto Parts in February 2020 and moved to the Freehold, New Jersey, site. They decided to focus on catalytic converter recycling and bought four decanning machines. These machines break apart the catalytic converters and demolish the cores into dust, which was then collected and sent to Dowa's refinery in Burlington, New Jersey. That year, DG Auto Parts bought a site in Emporia, Virginia, which they named DG Auto South, and began partnering with converter businesses across the US, including Curtis Cores. A neighboring business' manager said "people would come with tractor trailers and drop them off. Dumpsters full of cat[alytic converter]s. They were working 24 hours." Investigations would later reveal that DG Auto Parts did not care whether their supplies were obtained legally.

By 2021, the business had a website and an app for both Android and iOS which showed, for a subscription, the real-time pricing of thousands of catalytic converter codes, submit photos of their catalytic converters for advance grading and pricing and settle on a price prior to shipping their catalytic converters. The codes on catalytic converters identify the make, model and place of origin of catalytic converters, which in turn identify their value, due to variation in state emission laws. As an example, GD3 EA6 denotes a Toyota Prius manufactured between 2004 and 2009; at the peak of the PRP metal prices, its high palladium content could sell for more than $1,800.

As the profits grew, DG Auto Parts began making advance payments in the millions to their largest suppliers, including Curtis Cores, so that they too could provide their suppliers with the highest prices to maximize the supply of catalytic converters.

The investigation that led to the discovery of the theft ring began in late 2020 and early 2021, when a wave of catalytic converter thefts struck the Tulsa, Oklahoma area. Police began arresting "cutters", low-level criminals responsible for stealing catalytic converters. The police then attempted to get the cutters to reveal who they were selling to. According to the cutters, one such person was Steven Low Sr., an insurance agent and dealer in catalytic converters. In May 2021, GPS tracked Low's vehicle to an automobile recycling warehouse on Oklahoma State Highway 51 in Broken Arrow.

The warehouse was owned by Tyler Curtis, who was already of interest to investigators: in a February 2021 Facebook Marketplace exchange, Curtis had told an undercover investigator it "does [not] matter where they [the catalytic converters] came from...." On May 2, two days after Low's visit, the Tulsa Police Department stopped Curtis' vehicle, following a tip: an off-duty officer had spotted a "suspicious white pickup truck...with multiple catalytic converters in the bed" driving through southeast Tulsa. A search of the vehicle revealed contraband and other tools commonly associated with criminal activity: a loaded handgun; a small bag containing three grams of cocaine and eight grams of heroin; a bundle of cash amounting to $9,900; and 128 catalytic converters with jagged ends, suggesting that they had been stolen.

The officers then called a lieutenant, their liaison with the Federal Bureau of Investigation (FBI) regarding the theft wave. Questioned on where the catalytic converters came from, Curtis claimed that his automobile recycling business which had opened in January 2021, Curtis Cores, had obtained them legally.

Curtis and his passenger were then arrested for possession of drugs and an unpermitted firearm. To legally possess the catalytic converters, Curtis needed a scrap metal license, which Curtis did not possess; however, he said that his father had submitted an application for the permit. It was later discovered that, while he was in jail, he made a recorded phone call in which he asked his parents to remove incriminating objects from the warehouse. Curtis pleaded guilty or no contest in the Tulsa County District Court to the drug and firearm charges, receiving a three-year deferred sentence.

After releasing Curtis on bail, police obtained a search warrant regarding Curtis' seized phone and iPad. On these devices, they discovered a Facebook messaging group including Curtis, a man called Navin Khanna and another called Adam Sharkey.

By September, a team of investigators, led by Brad Staggs and the improbably-named Kansas Core, had identified that the stolen catalytic converters were being transported from across the US to a Freehold, New Jersey, company called DG Auto Parts where the cores were extracted and then shipped overseas.

In December, Kansas Core had obtained a warrant to place a 24-hour surveillance camera on a pole outside Curtis Cores. Vehicles arrived daily, sometimes hourly, full of catalytic converters. Curtis and his employees would then unload the converters, inspect them, and pay cash. Then the converters would be packed into cardboard boxes, wrapped in plastic and loaded onto pallets for transport. The business handled between 5,000 and 6,000 catalytic converters per week. These catalytic converters would then be transported either directly to DG Auto Parts or to Adam, an intermediary in New York.

Several weeks after Kansas Core gained the warrant to surveil Curtis Cores, he gained a search warrant for Curtis's Facebook account. Looking through his account, they—alongside a team associated with the Homeland Security Investigations (HSI) division in Tulsa—traced the development of the trafficking ring. Curtis had started working at Green Country Auto Core part-time three years before his arrest. Green Country's owner, Dave Edwards, trained Curtis extensively on the catalytic converter recycling industry and described Curtis as "good at his job [and] a hustler."

Between May and August 2020, Curtis found DG Auto Parts and put the owner, Navin Khanna, in contact with Edwards. Edwards would later say of Navin "I didn't deal with that guy [Navin Khanna] much. Curtis dealt with him...I did talk to the guy—just kind of rubbed me the wrong way." Court documents would later reveal that Green Country Auto Core had sold approximately $2,000,000 worth of catalytic converters to them. In late 2020, Curtis told Edwards that he would be starting his own business and that he would be bringing DG Auto Parts with him. Edwards later said of this "I felt I wasted a lot of time on him, showing him the business. Would've been nice to have a little warning, couple of weeks at least. In hindsight, it's probably the best thing that happened to me."

Kansas Core and other investigators started filing for more warrants: intercepting calls made to and from Curtis's phone, tracking the locations of his employees' phones, and monitoring their Facebook accounts. Another warrant authorized a pole camera outside Curtis's home, where he lived with his wife, on a large plot of land owned by his in-laws.

Since Curtis Cores had received stolen catalytic converters, he could be prosecuted in federal court. A regular delivery arrived from Houston, Texas, where the sellers specialized in "torpedo"-type catalytic converters – named for their distinctive shape – extracted from Toyota Tacoma and Tundra pickup trucks.

On March 31, 2022, in Houston, off-duty sheriff's deputy Darren Almendarez was grabbing groceries with his wife, and parked their Toyota Tundra outside of a Joe V's Smart Shop north of the city. Leaving the store, Almendarez noticed that a black Nissan Altima had backed up to his vehicle. Almendarez had worked in an auto theft unit in the Harris County Sheriff's Office and recognized an apparent catalytic converter theft in progress. As he approached, two men clambered out from under his truck and into the Altima, and he told his wife to run away and call the police. The driver of the Altima raised a handgun; Almendarez drew his own; in the ensuing shootout, Almendarez and two men inside the Altima were shot; and then the men fled.

Almendarez was rushed to Houston Northwest Hospital, where he was pronounced dead. Not long after, Joshua Stewart and Fredarius Clark arrived at the same hospital seeking treatment for gunshot wounds. Following treatment, they were taken into custody. A third suspect, Fredrick Tardy, was arrested the following day.

Houston police suspected that the three men delivered their stolen goods into a supply chain running through Tulsa. Staggs would later describe the Houston police as "highly motivated, obviously, to go out and take these people down...So we took this detour in our investigation to provide them with anything we could."

A week after Almendarez's death, the pole camera monitoring Curtis Cores recorded a black GMC pickup truck with Texas license plates pulling a U-Haul trailer of catalytic converters. The truck was traced back to Isaac Castillo, a Houston resident. Houston police had already stopped Castillo in February 2022, when he was driving a pickup carrying catalytic converters, discovering an unlicensed firearm and $25,000 in cash. Upon his return to Texas, police stopped Castillo again. Searching the truck, police discovered a box containing $206,000 in cash. Castillo continued to deny any wrongdoing, claiming that the money was a result of selling scrap in Oklahoma.

However, police continued to investigate, and identified Castillo as a member of a "Ley Road gang". Houston police and the Houston HSI alleged that the three men accused of Almendarez's death had been using the Ley Road gang and another gang as fences for the catalytic converters they stole. On July 28 that year, officers from Houston HSI, Harris County Sherriff's Office, Houston Police Department and the Texas Department of Public Safety raided the Ley Road gang, seizing over $484,000, 29 firearms, narcotics, a stolen Dodge Challenger SRT Hellcat and 477 catalytic converters worth an estimated $11–12,000,000. At the time, Castillo was not among those detained. The police obtained a warrant to locate his phone, which placed him at Curtis Cores making another delivery.

Shortly after leaving, Castillo was stopped by police for a third time, and this time arrested. Castillo would later tell investigators that Curtis kept $500,000 in his desk drawer and knew the catalytic converters he obtained and sold were stolen. When interviewed, one of the gang's leaders told police that Curtis had instructed him as to what vehicles to steal from.

According to court documents, Theodore Nicholas Papouloglou incorporated DG Auto South in Emporia, Virginia, in November 2020. He incorporated the business as a "scrap metal business" and a "money transmission business". Neither he nor the business were registered as a money transmitting business, as required by the Department of the Treasury and by Virginia laws. Papouloglou received over $12.2 million in wired payments from DG Auto Parts between 2020 and 2021. He bought stolen catalytic converters from thieves in the area, which would then be transported to DG Auto Parts for shipment to Dowa. He also helped DG Auto Parts to buy catalytic converters from other sellers across state lines, including from Texas and Oklahoma, paying for these in bulk cash payments, with the total paid out by Papouloglou being at least $6.6 million.

Despite this income, he paid no taxes on it during that time frame. A federal indictment was filed on March 19, 2024, including four counts; two of evasion of income tax assessments, one of conspiracy to transfer, receive, conceal and sell stolen goods and one of operating an unlicensed money transmitting business. An arrest warrant was filed that day. He pleaded not guilty to all counts the following day, however he later plead guilty to the first count of evasion of income tax assessments and to the count of conspiracy to transfer, receive, conceal and sell stolen goods on August 20 that year. The charges have a maximum penalty of 10 years imprisonment. He is awaiting sentencing, which is scheduled for February 20, 2025.

According to an indictment from July 2022, Tanner Hellbusch, who bought and resold cars and their components, began stealing catalytic converters sometime prior to February 2021. He was identified as a major local source of stolen catalytic converters, either stealing them himself or buying them from thieves and selling them on. At the time he lived with Jerrica Oga-Garo, his new fiancée, in Oak Hills, Beaverton, Oregon; he and his fiancée operated the business from their home, using the property to store catalytic converters and meet with buyers. Hellbusch placed advertisements on Facebook Marketplace looking for new suppliers.

In 2021, Oregon passed a law requiring that scrap metal businesses make a record of all catalytic converter purchases, including the vehicle identification number that they came from. This law also made it illegal to perform these transactions with cash. This led Hellbusch to try and find other buyers, leading him to begin selling catalytic converters through Brennan Doyle.

Doyle began his own business buying stolen catalytic converters from across the Western US in early 2021, with Hellbusch becoming one of his major suppliers. Doyle then found Adam Sharkey, after which he bought a warehouse in Aurora, Oregon, recruiting some of his friends to help him run the business. Jenna Wilson, with whom he had an intermittent relationship with, helped with the accounting, while Benjamin Jamison (who Doyle had known since high school) met with prospective buyers and handled transactions. By mid–2022, Brennan Doyle and Benjamin Jamison moved to a lakefront rental property on South Shore Boulevard, Lake Oswego, Oregon. The property was a two-bedroom house, costing $5,000 a month to rent. They also bought a $15,000 speedboat and held parties at the house.

An officer from the Beaverton Police Department and a detective from Clackamas County, Oregon, provided information that pointed towards Hellbusch being a major source of stolen catalytic converters. Based on this, the Beaverton Police Department began an investigation into the theft ring. By mid–2022, two dozen officers from various entities were surveilling the Lake Oswego property and the Aurora warehouse, however, the department had difficulties proving that Doyle knew he was receiving stolen catalytic converters.

In an effort to help prove this, the Oregon Department of Justice allowed the Beaverton Police Department to wiretap four phones, including Doyle's. Using these wiretaps and freight receipts, detectives unravelled the organisation and discovered Doyle's connection to Adam Sharkey. The wiretaps were so successful because of how indiscrete Doyle was with his dealings, he often called his friends to discuss the shipping of catalytic converters, which included who was performing the deliveries and what they contained.

Over mid–2022, Phillip Kearney, then assistant special agent in charge at the Oregon Department of Justice, began seizing the ring's assets and intercepting their wire transfers. Another alleged accomplice of Doyle, his childhood friend Casey Smith, complained online about how he was unable to access his bank account, losing access to $130,000. Later, Doyle and his alleged accomplices met to discuss whether their accounts had been frozen or whether the incidents were coincidences, and to discuss ways to get around their issues, unaware that Kearney had followed them.

A SWAT team raided Hellbusch's house while police raised the Lake Oswego property and the Aurora warehouse on August 3, 2022, discovering almost $40,000 in cash in Doyle's bedroom and 3,000 catalytic converters at the warehouse. 14 people were indicted by a grand jury, almost all of which were charged with various crimes including racketeering, theft and money laundering. Among them, Wilson, Jamison, Hellbusch and Oga-Garo were charged with theft and racketeering while Smith was charged with racketeering. Doyle was charged with 90 counts relating to aggravated theft, money laundering, racketeering and unlawfully receiving stolen metal, with Hellbusch facing 25 counts under similar charges.

In total, Beaverton police believe that the theft ring stole approximately $22 million in catalytic converters over the approximately two years it was operational, $10 million of which passed through Doyle, with chief deputy district attorney Bracken McKey stating in September 2022 stating that they still hadn't tracked all of the funds.

Despite the fact that Operation Heavy Metal was ongoing at the time, the investigation did not track catalytic converter thefts further than connecting the Sharkey's to the interstate theft ring, thus missing the connection to Oregon.

Following a rise in catalytic converter thefts in Weld County, Colorado, Weld County Sherriff's Office (WCSO) began investigating in 2021. This later led police to Elevation Auto Core in Brighton, Colorado. In 2022, the WCSO was contacted by the Colorado Bureau of Investigation and HSI. The investigation expanded to the state and federal level because Elevation Auto Core was a part of the larger theft ring, including a business in Las Vegas, Nevada.

Police tracked one of Curtis's employees to Elevation Auto Core on May 2, 2022, after which they discovered that the employee would soon be traveling back to Tulsa. The employee was stopped at the airport, where a cash-sniffing dog alerted officers to his bag, which contained $500,000 in cash. The employee signed over the money to the police.

According to arrest papers in the case, undercover officers and confidential informants wearing cameras found they could walk in and easily sell "obviously stolen catalytic converters". Despite changes to Colorado law requiring identification and other personal information to be collected in the sale of catalytic converters, little to no questions were asked in three different sting operations. The catalytic converters were then (similar to the Curtis Cores operation) packaged and placed onto pallets to be transported out of state (most of which were sent to the "east coast" or overseas) or decanned on-site.

Six men were taken into custody in both Colorado and Nevada on December 13, 2022, charged with violations of the Colorado Organized Crime Control Act, Colorado tax laws, theft, and money laundering.

From 2020 to 2022, four men from Minneapolis managed a theft ring where they acquired stolen catalytic converters and transported approximately 90% of their stock to "high-volume buyers based in New Jersey, Oklahoma, Colorado, and New York." They used similar methods to the rest of the ring: grading, pricing, sorting, concealing and then transporting the catalytic converters using rented U-Haul vehicles as well as their personal vehicles. In total, they received approximately $21,000,000 in payments using wire transfers, cash, cheques or a combination of methods.

Prosecutors said that the group took multiple trips to a buyer in New Jersey in 2021 before flying back to Minnesota, with at least three of these trips netting them a profit of nearly $500,000.

On May 2, 2019, Vang Auto Core LLC was started by Tou Vang, who was joined soon after by his brother, Andrew Vang. On May 31, Tou was arrested for the theft of a catalytic converter from a Prius. Between May 2 and October 1 that year, Vang Auto Core was already in contact with DG Auto Parts, with their first transaction occurring on October 1. In the following three months, the Vangs withdrew approximately $460,000 in $10,000 increments. This is likely due to the Bank Secrecy Act, a law requiring banks to report transactions larger than $10,000 to the Internal Revenue Service.

In September 2020, a Prius owner in Davis, California, discovered that their catalytic converter had been stolen. Investigation into the theft uncovered footage recorded by a vehicle on the same street, which showed a vehicle stopping near the Prius during the night, much like how the thieves had stopped behind Almendarez's vehicle in Houston. The vehicle and its owner were identified, and surveillance began. The following month, police stopped the vehicle and, upon searching it, discovered a number of catalytic converters inside. Two men were arrested in connection with this, Dao Xiong and Shaneel Lal. Prosecutors charged the two men with the theft of 64 catalytic converters in eight northern California counties.

During surveillance, investigators observed the two men casing neighborhoods during the day, only to return by night to steal catalytic converters. Investigators also tracked Xiong to the Vangs home on Meadowgate Drive, Sacramento.

The police acquired a search warrant for a phone confiscated from a known cutter in August 2020. In it, they discovered discussions between the cutter and a man called Choy Saeteurn, a mechanic based in Sacramento, regarding catalytic converters. Police then acquired a search warrant for Saeteurn's Facebook account.

With this search warrant, police discovered that on September 3, 2020, Tou and Saeteurn had a text conversation about Saeteurn returning to buying and selling catalytic converters, saying that he was doing so discreetly. Prosecutors later alleged that Tou was buying discreetly due to his prior arrest in 2019. By September 2020 however, he was already under investigation for the interstate trafficking of catalytic converters.

Navin communicated with Saeteurn a week later on September 10 about a need for more "Prius", referring to Toyota Priuses and their catalytic converters. In this conversation, he referred to Tou directly. The next day, Navin communicated with Saeteurn about Tou shipping 300 catalytic converters to DG Auto Parts. Bank records later showed that DG Auto Parts had paid Vang Auto Core $400,000 for the catalytic converters. In April 2021, shipping manifests showed that Vang Auto Core had shipped two crates weighing a combined 4,370 pounds (1,980 kilograms) to DG Auto Parts. In the two weeks following, DG Auto Parts paid Vang Auto Core a further $975,000.

Police began using a confidential informant to sell catalytic converters to the Vangs at their house some time between April and May 2021. Between then and August that year, the informant made five sales of between two or three catalytic converters at a time. On one occasion, the informant told the Vangs that he had stolen one from a Prius that he'd previously targeted. Andrew responded to this by saying "for future reference, don't say they were stolen."

During a conversation between the confidential informant and Andrew following the purchase of two catalytic converters in August that year, Andrew asked the informant to "see if you can cover it [catalytic converter] better" on return trips to the house, as another seller had "brought hella heat over here" not long prior by arriving in a stolen vehicle.

According to police, many of the cutters that sold to the Vangs were also related to the Tiny Rascal Gang (TRG). The TRG was founded in 1981 in Long Beach, California by Cambodian refugees seeking protection from neighboring gangs. Due to this and the fact the Vangs operated the business from home, the Vangs were known to keep at least five firearms in their house and more than 1,300 rounds of ammunition.

One of the Vang's neighbors, Joe McElroy, came back from work some time in November 2021, finding the street cordoned off by police; there was yellow crime tape surrounding the Vangs house and a tarp covering a corpse on the driveway. Upon asking around, he discovered that Andrew Vang had shot a burglar who had broken into their house. Not long after, he witnessed a "stream" of police entering the house with dogs and sledgehammers. McElroy later said of this "Cops come over and fucked up the whole house...Just ransacked it. Knocking the walls down. They destroyed it." The Vangs moved out within a few days, with the damage said to have taken approximately eight months to repair.

Due to the nature of the Vangs operation, investigators speculated that the perpetrators knew about their business and targeted their home expecting to find money there. Andrew was not charged for the shooting, as the shooting was deemed to have been self defense. When the Vangs left their home, they looked to DG Auto Parts to help them. In December 2021, the Khanna brothers paid approximately $1,200,000 for a house in northern Sacramento on their behalf.

By the second quarter of 2022, investigators already suspected that DG Auto Parts was the hub for the sale of stolen catalytic converters.

A Wyandotte Nation Tribal Police Department officer stopped a rental truck on May 8, 2022. During the stop a detection dog was used to search the vehicle and it indicated that it had found something. It was discovered that the vehicle was carrying three pallets of catalytic converters and approximately $1.3 million in cash. The driver, Robert Sharkey, "provided various mixed narratives to the purpose of his trip, or the source of the catalytic converters and money." The name Sharkey was already known to police in Tulsa due to his son, Adam Sharkey, DG Auto Parts' associate in New York. According to police, the money had originated from DG Auto Parts and approximately $290,000 was destined for Curtis Cores.

Robert was allegedly transferring money to another intermediary, Martynas Macerauskas, in Amarillo, Texas. Martynas was the owner of M&M Auto, a business in Clarendon, Texas who partnered with DG Auto Parts. He would later tell investigators about his dealings with DG Auto Parts, saying "Khanna does not care where the catalytic converters come from, only that he wants the volume so he can keep up with sales to Dowa."

Two days after Robert Sharkey was stopped, Martynas' wife was stopped in Texas with approximately $1.2 million in her vehicle; she told police that she had driven it from DG Auto Parts. In a search of M&M Auto, police found 30 catalytic converters. In total, the Macerauskas' received more than $6 million from DG Auto Parts for catalytic converters.

That same day, the pole camera surveilling Curtis Cores recorded Curtis's employees awaiting Robert's arrival. At approximately 3 a.m., Curtis was informed that Robert had been stopped and that the money had been seized. Curtis then called Adam to inform him. Two days after Robert Sharkey was stopped, Curtis flew to Newark Liberty International Airport and drove to DG Auto Parts while being followed by investigators. When he left, he was carrying approximately $1 million in bags which he then drove back to Oklahoma.

Curtis did become more careful upon returning after the Ley Road gang's then-recent arrest and concern that police would link them back to him, which was caught on a wiretap. He altered how he would buy stolen goods, refused to travel with large sums of money and would routinely check with his wife to ensure the money stashed around their property was safe. Despite this extra care, investigators used a confidential informant who went to Curtis Cores carrying 20 catalytic converters, who told Curtis that he had bought the catalytic converters from "a sketchy motherfucker" who had "just got them from some cars" and, after escaping from police, hid them in a field; Curtis still bought them.

Downpipe Depot & Recycling LLC in East Hartford, Connecticut, a buyer for DG Auto Parts, was raided by police in August 2022 after it was discovered that they transported and sold stolen catalytic converters to recycling businesses in New York and New Jersey. When federal investigators later obtained a wiretap for an employee of DG Auto Parts, they recorded Navin on August 5 telling him that traveling with money was too risky and that the police were "busting everybody".

An August drop in PRP prices, particularly palladium, strained DG Auto Parts' finances. One buyer threatened to sue the company for stealing data from the pricing app. There were accusations on their Facebook page that the brothers offered large sums of money for large quantities of catalytic converters and then refused to pay. In September 2022, DG Auto Parts announced that it had secured funding out of its financial difficulties with private investment firm Barrett Edge, who praised the Khanna brothers as "consummate professionals".

Meanwhile, investigators sent confidential informants to DG Auto Parts for months to sell catalytic converters, all the while emphasizing that they were stolen. In a Facebook message, Navin said, "every cat in Cali [is] stolen I can promise you that". Federal indictments later alleged that on September 1, a confidential informant claimed that their cousin worked in a Toyota warehouse and that they could steal catalytic converters and "bricks" (cores that had not yet been put into catalytic converters) from the Priuses stored there. The brothers agreed to the plan, paying $259,000 for 402 bricks and 98 catalytic converters.

By the third quarter of 2022, the investigation into the interstate catalytic converter theft ring was reaching its conclusion. Now nicknamed Operation Heavy Metal, the investigation had grown to include over 70 local and federal agencies. By chance, investigators in Operation Heavy Metal discovered the investigation into the Vang family; as such, the investigation was merged into Operation Heavy Metal. It was later discovered that Vang Auto Core had sold over $38,000,000 of catalytic converters to DG Auto Parts. The case had become so large that agents from multiple different agencies had to meet together in Philadelphia, Pennsylvania, to coordinate the final stages of the investigation.

On the morning of November 2, the owner of a store adjacent to Curtis Cores, Jeremy Jones of JT Auto, was in his office grabbing a cup of coffee when he witnessed the police storming into Curtis Cores. He later said of the day, "I look out the window and something caught my eye—it was like a SWAT team. There's a tank. There's guys with assault rifles and military gear." Curtis, who had left shortly before the raid, returned not long after and was arrested. Six of his partners and employees and his wife were arrested the same day.

Police used a helicopter and officers riding all-terrain vehicles to search unsuccessfully for the money stashed on his wife's family's land where he and his wife lived. Staggs said of this "he probably has money hidden somewhere that we'll never find". Curtis was accused of receiving approximately $13,000,000 from DG Auto Parts for the shipment of catalytic converters.

Simultaneously across the US, police executed more than 32 search warrants on locations used by the various organizations involved in the ring, seizing "homes, bank accounts, cash, and luxury vehicles", among other assets, which were valued at "tens of millions of dollars". In total, 21 arrests were made in five states. Seven people associated with DG Auto Parts were among those who were arrested, six of whom had been involved in decanning and selling the metals to refineries.

The Sharkeys gained approximately $45,000,000 from the sale of stolen catalytic converters to DG Auto Parts and were arrested in New York. Curtis received approximately $500,000 from Capital Cores, a company operated by Adam in Long Island, New York.

Over the course of their investigation, police discovered that Dowa Metals & Mining America had paid $545 million in revenue to DG Auto Parts. Prosecutors said that of the approximately $25,000,000 withdrawn from this sum by the Khannas, only $150,000 was recovered. As such, the Khannas were deemed to be a flight risk if released on bail. Despite surveillance and bank records proving Dowa to be the source of DG Auto Parts' money, the company's name was withheld during the indictments against Curtis and the Khannas, only being referred to as an unindicted co-conspirator.

Lauren Horwood, a spokesperson for the Eastern District of California US Attorneys Office, described Operation Heavy Metal as the first national takedown of a catalytic converter theft ring by the Department of Justice.

Staggs stated that Operation Heavy Metal had drastically cut the rate of catalytic converter thefts, saying "in the four months prior to that national takedown day, there were 250 reports of catalytic converter theft. In the four months after, there were 38." According to the NICB, by 2023 reports of catalytic converter thefts had declined significantly nationwide. In the first nine months of 2023, there were 2,675 catalytic converter thefts reported per month, down from over 5,000 in 2022.

A similar fall was registered in Houston, in March 2022 there were 1,200 catalytic converter thefts reported and on March 31 Deputy Almendarez was killed. The following month the number of reports dropped to approximately 950, falling gradually to 900 reports by July 2022. On July 28 the Ley Road Gang was raided, with the number of reports falling to approximately 400 by the end of the year.

The number of reports stayed steady until May 29 that year, which was when Senate Bill 224, known as the Deputy Darren Almendarez Act, became effective. The act aimed to "provide a framework of offenses, penalties and enhancements", with one of the enhancements being that if a firearm was used in the theft of a catalytic converter, the charge would become a felony. From then, the amount of reports fell gradually to almost zero by February 2024.

The government was seeking forfeiture of approximately $545 million in connection with the case; it is unclear whether they received this amount during the search and seizure efforts.

Janice Ayala joined Dowa Metals & Mining America as their Chief Compliance Officer on March 3, 2023. During Ayala's 27-year tenure at the Department of Homeland Security, her most recent role before joining Dowa was as Director of Joint Task Force – Investigations. This agency oversaw the investigation into both DG Auto Parts and Dowa.

Jamison pleaded guilty sometime between the 2022 Oregon indictment and 2024, while Doyle's trial is set for October 29, 2024.

The three men involved in the shooting of Darren Almendarez were later charged with capital murder. The District Attorney's office are seeking the death penalty for Joshua Stewart and Fredarius Clark, while Frederick Tardy, who was 17 at the time, was deemed too young. Tardy was released on a $750,000 bond. The three were awaiting court dates in April 2024.

Northeast Community Center in Houston was renamed the Deputy Darren Almendarez Community Center in his honor in August 2023, aiming to "keep his legacy alive in the very community that he and his family called home."

A superseding indictment was unsealed on March 20, 2024, charging Tinu and Navin's mother, father and older brother, Anita, Nirmal and Michael Khanna with conspiracy to transport stolen catalytic converters from California to New Jersey. The case alleged that, after Tinu and Navin were arrested, Anita, Nirmal and Michael continued buying and selling stolen catalytic converters under DG Auto Parts. The case also alleged that they sold the PRP metals to employees of a New Jersey metal refinery, including Alfredo Mejia and Vishnu Chintaman, via a broker, Ricky Vega, and that they knew the catalytic converters that the metals came from were stolen.