The downfall of Paul Calder Le Roux began with a routine act of police work — an undercover drug purchase by Minnesota DEA agents investigating illegal prescription websites.

But the Minnesota investigators soon found themselves chasing a target they never expected: A purported drug kingpin with links to international gunrunning, North Korean methamphetamines, Somali militias and the sudden deaths of those who tried to cross him.

Today, nine years later and thanks largely to their work, Le Roux is in U.S. custody and helping to build cases against those he once employed. And next month, the once-ghostly figure at the center of that empire is expected to appear in a federal courtroom in St. Paul as prosecutors proceed with a case against some of his alleged underlings.

Robert Richman, a Twin Cities attorney representing one of 10 men indicted in connection with the alleged online conspiracy, said Le Roux "has got to be the most vicious and diabolical criminal I've ever come across. There's really nothing that you can't put past that guy."

A grainy Brazilian airport security photo is the only image of Le Roux made public — a measure of his ability to stay in the shadows even as the world's law enforcement agencies closed in on him. Until recently, his name had been largely absent from federal court filings in New York and Minnesota, and his attorney has never been publicly identified, out of fear for his safety.

But interviews with federal investigators and Twin Cities attorneys, and hundreds of pages of court documents reviewed by the Star Tribune, reveal the most detailed portrait yet of a man long shrouded in mystery.

Alleged kingpin Paul Calder Le Roux may soon appear in federal court in St. Paul.

Born in the former Southern Rhodesia, Le Roux was adopted by a family in South Africa and, without graduating high school or college, taught himself mastery of a computer. That talent caught the attention of a German who lured him to Brazil to help with an online drug business, agents say. Le Roux eventually walked away, thinking he could do better. By the early 2000s, according to court filings, he was selling prescription painkillers online through his own company, RX Limited.

When DEA agents in the Twin Cities picked up the company's trail, it led them to a Chicago pharmacy that had been filling orders for the website's customers. Executing a search warrant there, they found the company's name all over the piles of FedEx packages scheduled for delivery.

RX Limited had a national account with FedEx and millions of customers. Prosecutors say it used websites and call centers around the world to sell prescription drugs — chiefly painkillers — without any doctor-patient relationship.

Investigators considered the business every bit as dangerous as heroin or meth, according to senior litigation counsel Linda Marks, who is prosecuting the case for the Department of Justice's consumer protection branch.

"Yes, it's not cocaine — but these are very dangerous, addictive drugs," Marks said at a 2014 hearing. "Some of those customers' hands are cold and 6 feet under right now."

The first suspect to plead guilty in the RX Limited case, late last year, was Jonathan Wall, a Kentucky man with dual U.S.-Israeli citizenship. Wall, who now awaits sentencing, said he managed call centers in the Philippines and the United States and hired pharmacists off Craigslist. But he also purchased boats, computer servers, dive equipment and an airplane on Le Roux's behalf and shipped them all over the world.

"He was not always aware of the intended use for some of the goods and equipment or its ultimate destination," according to Wall's Dec. 2015 plea agreement.

Authorities figure Le Roux made at least $400 million off RX Limited. But he remained a mystery until an investigator in Minneapolis plugging away at e-mail accounts found his name and a phone number he seemed to be using. Before long, authorities suspected Le Roux was up to something far more sinister than selling painkillers.

Activities intensify

The phone calls to Somalia caught the DEA's attention in 2009. So did the purchase in Turkey of a cargo ship by a company Le Roux owned. The ship wended its way around Africa to Indonesia, where it took on crates of high-powered assault rifles and pistols bound for the Philippines. Before customs officials raided the ship, its British captain escaped. But Bruce Jones, 50, later turned himself in and sought witness protection. Assassins on motorbikes gunned him down a year later north of Manila.

While working undercover purchases of drugs from RX Limited websites, agents in Minnesota were able to secure a wiretap to monitor calls from Alon Berkman, an Israeli citizen who managed the business' Internet infrastructure, shipping logistics and other operations. But they still didn't know Le Roux's location.

Then, in 2011, they came across a United Nations Security Council Report that shed light on where he had been. The report linked Le Roux to arming a Somali militia. His Hong Kong-based Southern Ace Ltd. — established as a shipping company for logging trucks — bought so many arms, including an anti-aircraft machine gun, "that local officials … noted a significant rise in the price of ammunition," the report said. Hallucinogenic plants were also cultivated at Le Roux's compound, the report said.

But Southern Ace left Somalia by early 2011 after Le Roux discovered he was unwittingly overpaying his militiamen.

In early 2012, investigators caught a break when Le Roux was spotted in Brazil. According to Brazilian news reports, he set up a front company there for his drug business; federal agents say he hoped to skirt extradition by fathering a child with a mistress and having his Filipino wife give birth there.

"He knows his circle is closing," an agent close to the investigation said. "He feels this."

The DEA worked with Brazilian authorities to get a wiretap on Le Roux's phone and heard him argue with an ex-wife over buying property in the Netherlands. The government would seize it anyway, he told her: "Everything we made in the U.S. was illegal."

Finally, in September 2012, U.S. agents were able to take Le Roux into custody after luring him to Liberia, which has an extradition treaty with the United States, in connection with a meth shipment.

Finding himself trapped, agents say, Le Roux first tried a tactic he'd admit worked well with other authorities: bribery.

"Wait, wait, wait," he said when that failed. Then: "I'm not getting on that plane."

Le Roux's face later bore red abrasions from the ensuing struggle.

"I'm sorry," he said on the flight to the U.S. "But I did warn you I would not cooperate."

He is now.

Feared boss made informant

Today, Le Roux, in his mid-40s, is in federal custody at an undisclosed location in New York state.

In what could be his first-ever public appearance, he has been called to federal court in St. Paul on March 2 by one of the alleged former employees he helped authorities capture in 2014.

Moran Oz, who is now in St. Paul on bail as he awaits trial, wants Le Roux to testify about whether he consented to surveillance of phone calls and e-mails between the two.

According to a DEA agent's affidavit, Oz was a "high-level manager" for RX Limited based in Jerusalem, handling the day-to-day operations of its pharmacies and physicians. Oz was one of two defendants arrested after Le Roux lured them to pick up a payment in Romania — easier than Israel for extradition purposes.

When the case goes to trial in June, Oz's attorneys also plan to call Le Roux back as a witness to bolster their argument that Oz worked under constant threat. Around 2009, after Le Roux suspected Oz of stealing from him, he told him to fly to the Philippines to meet some business partners. The men took Oz out in a boat and tossed him overboard once they reached open water.

Rifle fire pierced the water in a circular pattern around his head.

"That was to keep the sharks away," one man said. "The next one will be into your leg and then we will let the sharks eat you."

Oz talked his way back onto the boat and was held at sea for two days while another associate traveled to Jerusalem to check out his story.

"When we first heard that [story], we were a little skeptical," said Richman, one of Oz's attorneys. Then the same story surfaced in filings in a federal case out of New York against one of the men on that boat — a former U.S. Army sniper Le Roux employed who now faces a possible life sentence for plotting to kill a DEA agent and an informant.

Federal authorities in Minnesota say were it not for the DEA investigation initiated here, Le Roux would still be on the loose and in the shadows. A Justice spokeswoman said without the work of the Minneapolis investigators — along with the IRS, FDA and Postal Inspection Service — "this case wouldn't have developed as it did."

Still, some are a bit uneasy. Considering that a guilty plea he negotiated is under seal and the fact that he's been in custody for four years, it's possible Le Roux could be free again within six years.

Stephen Montemayor • 612-673-1755

Twitter: @smontemayor