A CARDBOARD BOX half the size of a loaf of bread bore a shipping label declaring its contents: “Adapter.” It was delivered in October to a Reuters reporter in Mexico City. There was no adapter inside that package.

Instead, sealed in a metallic Mylar bag was a plastic jar containing a kilogram of 1-boc-4-piperidone, a pale powder that’s a core ingredient of fentanyl. It was enough to produce 750,000 tablets of the deadly drug.

A Reuters reporter had ordered the chemical six weeks earlier from a seller in China. The sales assistant, “Jenny,” used a photo of a Chinese actress as her screen avatar. The price was $440, payable in Bitcoin, delivery by air freight included.

“We can ship safely to Mexico,” Jenny had written in Spanish on the encrypted message platform Telegram in July 2023, when the reporter first inquired about the chemical. “No one knows what we ship.” A Reuters reporter had ordered the chemical six weeks earlier from a seller in China. The sales assistant, “Jenny,” used a photo of a Chinese actress as her screen avatar. The price was $440, payable in Bitcoin, delivery by air freight included. “We can ship safely to Mexico,” Jenny had written in Spanish on the encrypted message platform Telegram in July 2023, when the reporter first inquired about the chemical.

“No one knows what we ship.” Anyone with a mailbox, an internet connection and digital currency to pay the tab can source these chemicals, a Reuters investigation found.

To learn how this global industry works, reporters made multiple buys of precursors over the past year. Though a few of the sales proved to be scams, the journalists succeeded in buying 12 chemicals that could be used to make fentanyl, according to independent chemists consulted by Reuters.

Most of the goods arrived as seamlessly as any other mail-order package.

The team also procured secondary ingredients used to process the essential precursors, as well as basic equipment – giving it everything needed to produce fentanyl.

The core precursors Reuters bought would have yielded enough fentanyl powder to make at least 3 million tablets, with a potential street value of $3 million – a conservative estimate based on prices cited by U.S. law enforcement agencies in published reports over the past six months. The total cost of the chemicals and equipment Reuters purchased, paid mainly in Bitcoin: $3,607.18. Turning these precursors into fentanyl would have required just modest lab skills and a basic grasp of chemistry. One Mexican fentanyl cook who dropped out of school at age 12 told Reuters he learned the trade as an apprentice at an illegal lab.

“It’s like making chicken soup,” said the cook, an independent producer based in the cartel stronghold of Sinaloa state.

“It’s mega-easy making that drug.” The Reuters reporters didn’t make fentanyl, had no intention to do so, and arranged for safe destruction of the chemicals and other materials they purchased. They also followed the guidance of lawyers before making the buys in an effort to ensure they complied with the law. Reuters is withholding detailed instructions and other information that could aid in synthesizing the drug. The dominant players in the illicit opioid trade – the Mexican cartels that manufacture most of the drugs and smuggle them into America– have been the subject of detailed reporting over the years.

Now, as the first news organization to buy and test fentanyl’s essential ingredients, Reuters has penetrated the hidden sub-industry that makes the cartel operations possible: the international supply chain of precursor chemicals.

The fentanyl business is largely a three-nation trading system, with the United States, Mexico and China linked in a toxic triangle as the illicit drug’s biggest consumer, manufacturer and raw-materials supplier.

The Reuters investigation has uncovered the names of Chinese sellers, the methods they use to ship their chemicals to North America, and how these packages evade customs inspections in Mexico and the United States. The ease with which the reporters bought the drug-making chemicals and gear exposes holes in the world regulatory framework, and shows how law enforcement is playing catch-up amid a profound transformation of the opioid market.

At the tap of a buyer’s smartphone, Chinese sellers will air-ship fentanyl precursors, sometimes falsely labeled as gadgets, cosmetics and other mundane goods. These packages are loaded onto planes stuffed with nearly identical-looking boxes of cheap exports that leave China by the billions every year. Major destinations are airports in Mexico and the United States, where the precursor-filled packages typically sail through customs with other merchandise, authorities in both countries said. There’s no need to ship bulky barrels of chemicals and navigate the tricky logistics of getting them onshore, as is the case for drugs like methamphetamine. “The game is different now,” said Christopher Landberg, deputy assistant secretary in the U.S.

State Department’s Bureau of International Narcotics and Law Enforcement Affairs. The supply chain is “more difficult to track, it’s more difficult to go after,” and fentanyl itself is “so much more deadly,” he said.

This flow is fueling alarming levels of fentanyl production, addiction and deaths. The street drug is the top killer of Americans aged 18 to 45, according to the U.S. Drug Enforcement Administration (DEA). Last year nearly 75,000 people died from overdoses of synthetic opioids, mainly fentanyl. While that’s down about 2% from 2022, no other illicit drug comes close to fentanyl’s toll.

President Joe Biden has made cracking down on illicit fentanyl supply chains a priority of his administration. A key element of this effort has been prosecution.

The U.S. Department of Justice (DOJ) has indicted at least a dozen Chinese chemical suppliers since mid-2023.

But at least three of those operators remained in business – and sold precursors to Reuters months after they were charged. One of these was Jenny’s company, which shipped Reuters the kilo of 1-boc-4-piperidone. In chats while arranging the sale, she scoffed at the U.S. crackdown. “We are a powerful company,” Jenny wrote in July 2023. “This incident has no impact on us.” In a written statement, Justice Department spokesman Wyn Hornbuckle said the DOJ and the DEA “will continue to aggressively investigate and prosecute every link in the fentanyl supply chain, including the chemical companies and executives in the People’s Republic of China supplying the ingredients used to make this deadly drug.” A senior White House official said the administration has vigorously attacked the fentanyl scourge at home and abroad. Those efforts include jump-starting bilateral cooperation with China on the issue, making record seizures of fentanyl entering the United States, and sanctioning hundreds of foreigners involved in the drug trade. The United States is saving lives through federal approval of an over-the-counter medication that rapidly reverses the effects of opioid overdoses, the official said. The administration is also looking to work with Congress to strengthen the reporting requirements for small shipments arriving in the United States, the official said, “so that we can better track, identify and target those packages which may contain finished pills, precursor chemicals, machinery and parts.” Reuters received 12 packages containing a total of 14 chemical orders at addresses in Mexico and the United States. Independent chemists consulted by Reuters said 12 of the chemicals were fentanyl precursors. The remaining two were fakes: one sugar and the other lidocaine, a local anesthetic. The chemical Reuters bought from Jenny was one of 16 that reporters ordered from various precursor suppliers from August 2023 to May 2024. Fourteen of those chemicals were delivered: six to Mexico City, seven to a rented mailbox in New Jersey, and one to an apartment in New York City. Some boxes arrived bearing fake labels, including “doorknob” and “hair accessories.” Two precursor chemicals came sealed in cat food bags. Independent chemists consulted by Reuters said that 12 of the delivered chemicals, totaling 6.6 kilos, could be used to make fentanyl. Four of Reuters’ buys were rip-offs: One shipment contained sugar. Another was lidocaine, a local anesthetic. Two sellers failed to deliver anything. The reporters also bought a pill press, two die molds and a binding agent that could be used to produce small, light-blue tablets stamped with an “M” on one side and the number “30” on the other. Those are the signature markings of a generic version of the prescription painkiller oxycodone. Use of illicit fentanyl soared as a substitute for that highly addictive drug, and the copycat look has stuck. Much of the illegal fentanyl sold in the United States still comes in the form of blue M30 pills, authorities say. In all, eight suppliers delivered authentic fentanyl precursors. Seven of those were based in China, the world’s largest exporter of chemicals. Reporters traced the country of origin through phone numbers used by the sales agents, shipping records for the packages and other means. Washington has been pushing China and Mexico to do more to keep fentanyl precursor chemicals from reaching illicit manufacturers. Those countries defend their efforts and say the U.S. needs to tackle its addiction problem. Amid the finger-pointing, chemical suppliers have little trouble evading what regulations do exist, because hundreds of different chemicals can be used to make these synthetic opioids. Many sellers have stopped offering “immediate” precursors: chemicals that are the easiest to turn into fentanyl and face the toughest controls. Instead, these suppliers sell the ingredients that are used to create the immediate precursors. These alternatives, or “pre-precursors,” require just minor extra steps to make fentanyl. Another trick is to tweak the chemical structure of a precursor to circumvent regulations. Such “designer” precursors can still be used to make fentanyl or one of its analogs, which are often just as potent as fentanyl, or even more so.

The upshot: When authorities restrict one chemical, suppliers and traffickers just switch to another, said Rahul Gupta, director of the White House Office of National Drug Control Policy. “It’s whack-a-mole,” Gupta said of government attempts to regulate fentanyl ingredients. The Reuters purchases illuminate why.

Most precursors the reporters bought were piperidines – a group of chemicals essential to making fentanyl, but which also are used to manufacture ordinary products, including insecticides and fragrances.

U.S. and international regulators have imposed some restrictions on these chemicals in recent years in an effort to keep them from illicit fentanyl manufacturers. But in America, and elsewhere, trade in most precursor materials is legal when they are purchased for legitimate business or research purposes.

The focus of many U.S. laws is on the intent of a transaction, making it a federal crime to buy or sell such otherwise legal chemicals with the aim of making fentanyl. The Reuters reporters had no intention of making fentanyl with the precursors they purchased, and took no steps to do so.

In China and Mexico, the chemicals they bought generally aren’t banned or restricted.

The journalists bought no immediate precursors. Their ability to readily obtain fentanyl ingredients demonstrated the challenge of plugging the precursor pipeline, said Todd Robinson, head of the U.S. State Department’s Bureau of International Narcotics and Law Enforcement Affairs. He said authorities are balancing efforts to protect the public by stanching the flow to illicit producers without imperiling legitimate industries that rely on these chemicals. “We continue to want to walk that fine line,” he said.

“It’s not easy.” Many Chinese suppliers, by contrast, openly marketed their wares as ingredients for illicit drugs. Two sellers, for instance, provided molecular diagrams of fentanyl precursors – along with instructions on how to chemically tweak them to get them ready to be synthesized into fentanyl. China has taken some steps to constrict the pipeline. In 2019, it placed fentanyl and its analogs under national control, effectively ending illicit exports of the finished product. Last year, China warned chemical exporters not to violate foreign drug laws. But it has yet to control three common fentanyl-making chemicals that the United Nations Commission on Narcotic Drugs in 2022 added to a list of precursors that member states – including China – are required to regulate.

Liu Pengyu, spokesperson for the Chinese Embassy in Washington, said in a statement that China is close to implementing controls on three fentanyl precursors. It’s also “cracking down on illegal activities involving smuggling, manufacturing, trafficking and abuse of fentanyl substances and their precursor chemicals” as part of a special campaign, Liu said. He did not address questions about why Reuters was able to buy fentanyl-making chemicals and equipment from Chinese suppliers who were openly catering to the illicit drug trade. But Liu said China is targeting online advertising related to fentanyl and its precursors, and has shuttered 14 online platforms, closed 332 company accounts, terminated 1,016 online stores and erased more than 146,000 online posts. Beijing has tough anti-narcotics laws, he added. “Scapegoating others, especially China that has been trying to help, cannot resolve the U.S. problem of fentanyl,” Liu said. “What the U.S.

needs to do is to reduce domestic demand, strengthen prescription control, (and) step up (its) drug awareness campaign.” In Mexico, lawmakers last year increased reporting requirements for legal trade in precursor chemicals and stiffened criminal penalties for illicit use. But many fentanyl-making chemicals are still not included in this legislation. Unlike in the United States, where narcotics regulations can be updated by federal agencies, in Mexico, lawmakers must usually approve significant changes, making for a lengthier process. The office of Mexico’s attorney general, which investigates and prosecutes drug crimes, did not respond to requests for comment. Nor did the foreign ministry, the national customs agency or the office of the presidency.

U.S. controls, too, have gaps. Reuters obtained the final precursor it needed from a U.S. chemical wholesaler – using one of the world’s most popular online shopping sites. Fentanyl marked a breakthrough in pain management when it was introduced in the 1960s, after being developed by Belgian chemist Paul Janssen. At the time, it was the most potent synthetic opioid ever created and went on to become a mainstay in hospitals to ease surgical pain. It and other synthetic opioids are still legally produced and widely prescribed for sedation and pain relief. Like heroin, fentanyl delivers a euphoric high. An overdose can cause fatal respiratory failure. Fentanyl found its way to U.S. streets in the 1970s as “China White,” a niche form of heroin flecked with fentanyl. But the real explosion came in the 2010s on the back of epidemic abuse of prescription painkillers such as Purdue Pharma’s OxyContin, a version of oxycodone. After the U.S. made it tougher for doctors to prescribe these meds, some users turned to illicit fentanyl. At first, street fentanyl was made in China and sold through so-called dark web marketplaces. When Chinese fentanyl exports dried up in 2019 after Beijing’s crackdown, Mexican cartels took over manufacturing the finished product. Chinese chemical producers supplied cartels with raw materials, according to law enforcement officials. Some of these ingredients go straight to Mexico. But the U.S. has become an important transshipment hub. The sheer volume of merchandise arriving daily in America on flights from China makes it easy to sneak in small boxes of chemicals. Narcos then route the precursors to labs in Mexico and send finished fentanyl north to the United States.

U.S. Customs and Border Protection data show an explosion of fentanyl seizures at the Mexican border in recent years. Since 2015, the U.S. overdose death rate has doubled, reaching 32.6 per 100,000 people in 2022, according to the Centers for Disease Control and Prevention. One factor driving the deadly toll: Fentanyl is far more potent than oxycodone and other prescription opioids. Another: It is a cinch to make. There’s no need for vast tracts of land to grow crops, as is the case with cocaine (made from coca leaves) or heroin (derived from opium poppies). Compared to the synthetic drug meth, fentanyl is safer and simpler to produce and requires smaller amounts of chemicals, chemists say. That efficiency is due partly to an innovation by scientists with India’s Ministry of Defense. The team was tasked with finding a simplified method of producing the surgical analgesic to help treat battlefield injuries, and in 2005, it published a streamlined process for synthesizing fentanyl. The procedure is known as the “Gupta method,” after the main author of the paper, Pradeep Kumar Gupta. Illicit fentanyl makers would embrace the technique and put their own spins on it. Descriptions of the process are now widely available online. Gupta could not be reached for comment. India’s Ministry of Defense did not respond to a request for comment. In assembling a fentanyl shopping list, Reuters followed a version of the Gupta method popular with illicit manufacturers. The process requires a piperidine-based compound and three additional precursors – (2-bromoethyl)benzene, propionyl chloride and aniline – as well as a handful of secondary ingredients. The reporters began by looking for supplies on the dark web, a corner of the internet rife with illicit commerce. Accessing it requires the use of an anonymizing web browser to keep everyone’s identity and location secret. The team first scored at a drug marketplace called Breaking Bad. The name is a nod to the American television series about a meth-cooking antihero. The site’s moderator goes by “Heisenberg,” the nickname of the protagonist. Dozens of sellers there offered various chemicals needed to manufacture illicit drugs. Many touted the phony packaging they used to disguise shipments, including engine oil containers and bags of coffee. In response to questions submitted by Reuters, site administrator Heisenberg said Breaking Bad is a marketplace for some types of drugs, but that fentanyl and its precursors are “poisons” whose sale is prohibited on the site. Reuters, however, purchased fentanyl precursors last year from two sellers who advertised such chemicals on the platform. It turned out that prowling the dark web wasn’t necessary to find precursors: Vendors abound on the regular internet. Reuters located sellers via their company websites, on an international chemical marketplace, and through crude digital advertisements scattered across the Web. Those ads all followed the same pattern. Almost every known chemical has been assigned a unique code that’s listed in an official chemical industry registry.

Sellers create simple ads by superimposing a precursor’s code – CAS 40064-34-4, for example – over a photo of white powder, along with a phone number. Such an ad would signify little to most shoppers. But fentanyl makers searching for chemicals by their registry numbers would find hundreds of these ads in what amounts to a handy digital directory of suppliers. In total, three Reuters journalists interacted with nearly 50 different sellers. The sales agents insisted on communicating via secure message channels such as Telegram, Signal and WhatsApp. The chats were mostly in English, occasionally in Spanish. If a sale was agreed upon, the reporters paid for the goods, almost exclusively in crypto. The reporters conducted the deals using message-app usernames, as is standard on the sites, and weren’t asked to provide their full names. Most sales agents used feminine Western names, including Mary, Phoebe, Daisy, Sara and Justine. Their profile pictures were mostly of young, attractive Asian women. A seller who gave her name as Xiao Tong admitted in a March 2024 chat that her photo wasn’t genuine. “But I look good myself, haha,” she wrote on WhatsApp. Simon, a seller at another outlet, was eager to help a potential customer make the right selection. He confirmed that a chemical Reuters inquired about could be used to make fentanyl, but suggested an efficient alternative. “Subsequent production steps are reduced, you can study it,” Simon wrote in an August 2023 Signal chat. To vet that advice, Reuters consulted Alex J. Krotulski, a chemist who studies illicit drugs at the nonprofit Center for Forensic Science Research and Education near Philadelphia. He confirmed that Simon’s recommended precursor would, in fact, take fewer steps to transform into fentanyl. A sales rep named Sunnee was even more explicit. During a chat in April on Telegram, Sunnee sent a molecular diagram of “the best piperidine product.” Sunnee followed up two days later with instructions on how to chemically change the compound so that it could easily be turned into fentanyl. “Keep stirring until a large number of bubbles overflow from the mixing barrel,” one of the steps read. Krotulski said Sunnee’s instructions were sound. Seven Chinese suppliers accounted for 11 of the 12 authentic precursors Reuters bought. Reporters found two of these sellers on Breaking Bad, one through the online marketplace ChemicalBook, and one via the vendor’s website. Reporters located the other three Chinese suppliers via digital ads – one that appeared on the audio platform SoundCloud, and two that surfaced in Google Image searches. ChemicalBook didn’t respond to requests for comment. SoundCloud said that it, like other social media platforms, has been “targeted by bad actors for the purpose of advertising illegal drugs and dangerous substances.” The company said it’s boosting investment in content moderation to identify and remove such ads. Google said it relies on local laws and court decisions to determine whether content is illegal and should be removed from its search results. It said Google Image queries for these ads were “very uncommon” and that it has received no official guidance with respect to culling them from search results. While it was easy to source the goods, it proved far more difficult to identify exactly who sold them. Reuters couldn’t determine whether any of the Chinese suppliers were the actual manufacturers of the chemicals received or simply middlemen. Nor could the news organization determine where the operations were located. Reporters could dig up nothing more than phone numbers for two of the sellers. For the others, corporate websites and Chinese business-registry documents yielded addresses. But when Reuters visited these locations, it found no visible presence of the companies there. The address listed in a government database for a precursor seller known as Hubei Amarvel Biotech, for example, led to a Wuhan office tower. A visit to the listed room number showed another company occupying that space, while the building’s management told Reuters that the chemical supplier had never rented space there. Amarvel is the operation that sales agent Jenny worked for. It is one of three Chinese suppliers that sold Reuters precursors after having been indicted last year by U.S. federal prosecutors. The Justice Department accused Amarvel of exporting “vast quantities” of chemicals used to make fentanyl and similar drugs. Two Amarvel suspects – Wang Qingzhou and Chen Yiyi – are in jail awaiting trial in New York. They have pleaded not guilty. A third, unidentified suspect remains at large. Wang’s attorney, Leonardo Aldridge, and Chen’s attorney, Marlon Kirton, declined to comment. A Mexico-based Reuters reporter initially contacted Amarvel via Telegram in July 2023 to inquire about fentanyl precursors, a few weeks after the grand jury indictment was unsealed in New York. Sales agent Jenny denounced U.S. drug policy and the case against the company. “What we sell is completely legal in China, but the United States always uses this matter to criticize us, and they even pose as buyers to get our information and slander our country,” Jenny wrote in Spanish. “I hate all Americans, they use it (fentanyl) themselves and blame us.” Two other suppliers to Reuters have been indicted in separate cases by federal prosecutors in Florida. One is Anhui Ruihan Technology. It was charged with attempted importation of fentanyl precursors and attempted international money laundering, according to a grand jury indictment filed in September 2023. No one has been arrested in that case. Anhui Ruihan’s website continues to offer chemicals that can be used to make illicit drugs. Reuters purchased one kilogram of the fentanyl precursor (2-bromoethyl)benzene for $150 from the company in March 2024. Anhui Ruihan did not respond to requests for comment. Also indicted was Jiangsu Bangdeya New Material, a pharmaceutical company in Jiangsu, China. It was charged along with its alleged owner and operator, Wang Jiantong, in September 2023. The charges included conspiracy to import and distribute protonitazene and metonitazene – synthetic opioids that traffickers mix with fentanyl to create even more powerful drugs. Wang was declared a fugitive in October 2023 by a federal judge in Miami. Wang could not be reached for comment. Jiangsu Bangdeya continued to sell synthetic opioid ingredients. In May 2024, Reuters purchased the fentanyl precursor propionyl chloride from a company sales agent named Lara. In June, Reuters followed up with all the companies and sales agents from whom it had purchased chemicals and equipment to explain that these transactions were part of an investigation of the fentanyl supply chain. The news agency asked them a set of questions. Lara of Jiangsu Bangdeya was among the few who responded. In a WhatsApp chat in June, she defended the May sale of propionyl chloride, saying the chemical is legal in China. She sent a list of its uses, including the manufacture of medicines and pesticides. Lara said her company follows Chinese law and that it wasn’t her responsibility to know how foreign customers would use the products abroad. “This product is legal in our country,” Lara wrote. “But I don’t know what you will do with it when exported to your country.” In online ads, the company listed a piperidine whose only known use is to manufacture fentanyl. Jenny, the seller for Amarvel, denied selling fentanyl precursors to Reuters or any other buyers in a Telegram message in June. Asked whether Amarvel or Beijing shared some of the responsibility for the U.S. fentanyl crisis, she bristled. “If you think the Chinese government is responsible to the United States, fuck you, Yankee,” she wrote. The Chinese Embassy in Washington and China’s Ministry of Public Security didn’t respond to questions about why Amarvel, Anhui Ruihan and Jiangsu Bangdeya were still operating after being indicted by American authorities. But the ministry said Chinese anti-narcotics agents have stepped up cooperation and intelligence-sharing with their U.S. counterparts. These steps are bearing fruit, it said, such as the recent arrest of a Chinese national accused of laundering drug money for Mexican drug cartels. Reporters also obtained a pill press and a metal mold that could be used to make counterfeit M30 tablets from a Chinese supplier called Besttabletpress.com. The price was $450.99. Pill presses are illegal for individuals to buy or own in Mexico without government authorization.

The U.S. generally allows such sales, as long as the equipment isn’t used for illicit purposes, among other requirements. Reuters had the pill press shipped to the United States. Besttabletpress.com is candid about one potential use of its products. In a June 2023 post, the site’s unnamed administrator explained “how to make M30 tablets with a manual press die.” Besttabletpress.com did not respond to requests for comment sent by Reuters in mid-June, and a man who answered the phone at the number listed on the company website said a reporter had the wrong number. The site was taken down soon afterwards. The DOJ’s Hornbuckle said the DEA routinely investigates transactions involving pill-stamping machinery that can be diverted to the illicit fentanyl trade. He described U.S. regulatory requirements on fentanyl precursors and related equipment as “robust” and said violators face a host of penalties, including criminal prosecution.

In November, China’s National Narcotics Control Commission advised chemical manufacturers and brokers to be wary of selling precursors where they are controlled or illegal, such as Mexico and the United States, warning they could face charges in such countries.

The guidance also cautioned companies to watch out for “long-arm jurisdiction” and “phishing law enforcement” – apparent references to U.S. anti-narcotics investigators who have been running sting operations against Chinese firms.

The Chinese Embassy in Washington declined to elaborate.

To gauge the guidance’s impact, Reuters contacted Jenny at Amarvel in February. This time, a different reporter, using a new phone number, sought to buy more chemicals, for delivery to the United States instead of Mexico.

Jenny said the company no longer shipped fentanyl precursors anywhere in the Americas. “China police ask us be careful USA spy,” Jenny wrote in English.

“They pretend buyer.” Jenny offered to send fentanyl precursors to Germany or other places outside the Americas. Drug traffickers sometimes use Europe to transship Chinese chemicals to Mexico, according to security sources.

Reuters opted not to make a second purchase from Jenny, but found other sellers willing to ship to the United States.

One was Anhui Ruihan, which sold Reuters the kilogram of (2-bromoethyl)benzene in March. This essential ingredient for fentanyl is also used to make pharmaceuticals and fragrances.

The liquid arrived in the United States less than two weeks after it was ordered. But there was a hiccup in the delivery. The air freight package arrived from China at FedEx’s main U.S. hub in Memphis, Tennessee, labeled “PIGMENT INK.” That triggered a reporting requirement.

U.S. law requires chemical importers – in this case, the Reuters journalist listed as the recipient of the “ink” – to affirm that the purchase complied with the Toxic Substances Control Act. FedEx notified the journalist he would need to complete a form attesting to compliance with the law, along with the name and value of the chemical, to get the package through customs. Anhui Ruihan was also informed of the delay. It sent both FedEx and the reporter a completed form listing the contents as pigment ink worth $10. The Anhui Ruihan agent said all the document needed was the journalist’s signature so that U.S. Customs would release the package for delivery. The reporter didn’t sign that document. He submitted an accurate declaration to FedEx, listing the purchased chemical as (2-bromoethyl)benzene, valued at $150. That same day, U.S. Customs cleared the package, and FedEx delivered it to New Jersey less than 24 hours later.

Asked why the shipment was allowed in, FedEx said (2-bromoethyl)benzene is not on the DEA’s controlled substances list and that its team members followed the correct procedures based on the information provided. U.S. Customs declined to comment on specific purchases made by Reuters. But a senior agency official said the story highlighted the need for strengthening U.S. laws and regulations on small packages entering the country, and for improving intelligence and cooperation with China to stop fentanyl chemicals before they arrive on U.S. shores. "We can't seize our way out of the fentanyl threat," she said. "We have to be working collaboratively across the U.S. government and with our foreign partners." Two days later, three Reuters journalists met chemist Krotulski at his laboratory in leafy Horsham, Pennsylvania.

They brought along a red duffle bag. Inside was the bottle of (2-bromoethyl)benzene and a pair of Mylar bags containing two powdered chemicals purchased from other suppliers. Krotulski’s employer, the Center for Forensic Science Research and Education, tests drug samples for law enforcement agencies, addiction treatment centers and other clients.

Krotulski, the director for toxicology and chemistry, checked the Reuters buys to determine whether they were authentic. He placed small amounts of each chemical in test tubes, mixed the substances with an organic solvent and put them in three vials. Then he ran the vials through a mass spectrometer, a machine that detects the molecular makeup of chemicals.

The verdict: The clear liquid was the real deal: (2-bromoethyl)benzene. Next up was one of the powders. It was supposed to be para-fluoro-4-AP. The chemical turned out to be lidocaine, a topical analgesic commonly used to cut cocaine, but not as a fentanyl precursor. A fake. Reuters had bought it for $380 in Bitcoin in March. The third substance, too, wasn’t as advertised. It was meant to be 1-boc-4-AP, a fentanyl precursor that’s regulated in the United States, but unregulated in China. It turned out to be para-fluoro-boc-4-AP. Krotulski said para-fluoro-boc-4-AP is a closely related chemical that fentanyl cooks can substitute into their usual process. The final product would be fluoro fentanyl, an analog indistinguishable from fentanyl in its effect. “It’ll still get people high,” Krotulski said.

Reuters bought the para-fluoro-boc-4-AP in February 2024 from sales agent Sunnee at Shandong Xiju Biotechnology, for $260 in Bitcoin. The company didn’t respond to requests for comment. There was another surprise in the deal with Sunnee: Her company sent just 100 milligrams of the precursor rather than the kilo Reuters had ordered. To make up for it, Sunnee offered the chance to purchase a new, and thus unregulated, chemical. Reuters accepted, paying $150 in Bitcoin. Sunnee sent a hand-drawn diagram of the compound via Telegram, along with instructions on how to chemically alter the substance so that it could easily be transformed into fentanyl. The instructions referred to the chemical as BOC-X. In early May, a journalist returned to Krotulski’s lab with 300 grams of the mystery powder.

Krotulski’s colleague Joshua DeBord ran a sample of the khaki-colored substance through the spectrometer. The results stumped him. He didn’t recognize the compound’s “signature,” a pattern displayed as spikes on the monitor indicating the presence of particular chemical groups. It didn’t match anything in the lab’s database of hundreds of thousands of chemicals. Krotulski followed up a day later. After comparing the signature with the nearest matches in the database, he had concluded that BOC-X was very close to what Sunnee had promised. It was not on the list of U.S.-regulated chemicals. It could be used to make a version of fentanyl. And while it wasn’t entirely novel, Krotulski said it was a little-known designer precursor. He dubbed it ortho-methyl-boc-4-AP, after its unique molecular structure. His discovery highlights how chemical suppliers and fentanyl makers try to stay a step ahead of U.S. officials by cooking up ever more obscure piperidine compounds.

When Reuters received delivery of the BOC-X in New Jersey in May 2024, the box was sealed with a strip of green tape bearing the words: “U.S. Customs and Border Protection. EXAMINED.” Translation: U.S. Customs stopped the package when it reached U.S. soil, took a look inside, and sent it on its way. The tracking information didn’t note where the inspection occurred.

An identical chemical from a different seller showed up a week later in Mexico City, in a box labeled “computer accessories.” Inside were two vacuum-sealed bags of “full price kittens food,” each concealing a powdered chemical.

Testing at the Institute of Chemistry at the National Autonomous University of Mexico confirmed that the substance was an authentic piperidine precursor. Reuters had bought these from Wuhan Hantian Biotechnology in April, paying a total of $750 in Bitcoin. The sales rep, Xiao Tong, was the agent who had admitted that her avatar was fake.

Later, in June, Reuters followed up with Xiao Tong to seek her comment on the precursor sales. She said her boss had told her the company didn’t sell drugs and that she didn’t know that thousands of people die every year from fentanyl overdoses. She said she’d recently quit the job. As for the piperidine precursor she’d sent Reuters, “if it harms people, it’s a good thing that you are a reporter and haven’t circulated it,” she said. Having obtained several packages of authentic piperidines and two other precursors, the reporters had three of the four essential ingredients on their shopping list. The Gupta method called for just one more: aniline. An unregulated fentanyl precursor, aniline is also widely used by makers of pharmaceuticals, rubber, explosives and textiles.

A quick search online turned up a source: Amazon.com. A reporter ordered and received a 100-milliliter bottle of aniline through the e-commerce giant’s marketplace from Carolina Chemical, a North Carolina-based supplier of industrial chemicals. Robert Smith, chief executive of Carolina Chemical, said his company doesn’t manufacture the aniline it sells and declined to disclose his source of supply. Carolina sells very little aniline, he said, and requires customers to state why they’re purchasing certain chemicals when stipulated by law. Amazon noted that aniline is a legal and widely available product. The online retailer said it requires all the goods it offers to comply with applicable laws, regulations and company policies.

Reuters also placed orders for the remaining and highly common secondary ingredients of fentanyl, including ammonia and acetone, and for a protective suit, a full-face respirator, beakers and other gear. All were purchased on Amazon.com and arrived within two weeks.

With that, the reporters had all it takes to produce one of the deadliest highs on earth.