Paul Calder Le Roux, the mastermind behind a global business in drugs and gunrunning, made his first public appearance in an American courtroom Wednesday morning, calmly detailing a list of international crimes that includes seven murders.

Under the watch of U.S. marshals at the federal courthouse in St. Paul, Le Roux calmly answered a barrage of questions about his empire and his relationship with Moran Oz, one of several co-defendants in a prescription drug conspiracy case brought by prosecutors in Minnesota.

Since much information about the case, including Le Roux's plea agreement, has been sealed under court order, Moran's defense attorney Robert Richman was trying to evince information for the defense during the three-hour hearing.

"Beneath that calm exterior is a ruthless killer," Richman said after the hearing.

Le Roux, who is in his mid-40s, was never flustered by Richman's questions about drug and weapons deals and his cooperation as a government witness against several of his alleged underlings. He often played with his fingernails, only occasionally lowering his gaze away from Richman.

Le Roux first came to the attention of federal investigators in 2007, when DEA agents in Minnesota stumbled upon one of his businesses, RX Limited, which sold prescription drugs online using a pharmacy in Chicago. After his capture, he helped the government build a case against other men associated with the business, according to documents reviewed by the Star Tribune.

Le Roux was captured by U.S. agents in Liberia four years ago. He had traveled to Liberia from a base in South America to set up a methamphetamine lab for a Colombia drug cartel in exchange for cocaine, he said.

In January, Keyes granted a motion by Oz, who is now in St. Paul on bail awaiting trial, to compel Le Roux to appear. It was the first time the men had seen each other since Le Roux's arrest.

Le Roux has been in federal custody at an undisclosed location in New York state since DEA agents captured him in 2012. He has negotiated guilty pleas under seal that could result in a lightened sentence, according to Star Tribune interviews with federal investigators and Twin Cities attorneys.

According to a DEA agent's affidavit, Oz was a "high-level manager" for Le Roux's 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, where U.S. extradition would be easier.

Authorities figure Le Roux made at least $400 million off RX Limited from 2004 to 2012.

In 2013, the Department of Justice's consumer protection branch filed charges against 11 defendants in federal court in Minnesota. Five are awaiting trial in the case while three others remain fugitives — likely outside the country. Charges against one man were dropped and another, Jonathan Wall, pleaded guilty in December.

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 for him 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 in shark-infested waters.

Keyes is expected to make a decision on Wednesday's motion in about three weeks.

Stephen Montemayor • 612-673-1755

Twitter: @smontemayor