Six people have been indicted on suspicion of being involved in a multimillion-dollar drug trafficking ring based in a Cottonwood Heights basement, the U.S. attorney's office announced Wednesday.

The operation allegedly sold fentanyl-laced pills pressed to look like tamer prescription drugs, said U.S. Attorney John Huber at a multiagency news conference.

The charges come six months after an initial indictment against Aaron Shamo, now 27, who was arrested in November when police seized drugs worth millions of dollars on the street, according to court documents.

Customers throughout the nation ordered pills online, according to the documents.

Shamo and Drew Crandall allegedly imported fentanyl and alprazolam painkillers from China, then used a pill press to make fake Oxycodone and counterfeit Xanax, documents stated. They laundered money through bitcoin and accepted the digital currency as payment for drugs, said John Eisert, special agent in charge for Homeland Security.

Shamo and Crandall started the organization together, according to court documents. As it grew, they brought in others to accept shipments and to package pills.

In addition to Shamo, a federal grand jury charged four Utahns — Alexandrya Maria Tonge, 25, Katherine Lauren Bustin, 26, Mario Anthony Noble, 28, and Sean Michael Gygie, 27 — and Crandall, 30, who is from Brisbane, Australia, but lived in Utah.

Shamo, whom investigators identified as the leader of the organization, faces 12 counts, including intentionally engaging in a criminal enterprise, possession with intent to distribute a controlled substance, conspiracy to commit money laundering and using the U.S. mail to traffic drugs. A conviction of the most major crime, involvement in a criminal operation, carries a mandatory life sentence in prison.

The investigation included agents from the Homeland Security Department, the Drug Enforcement Agency, the U.S. Postal Service, the criminal investigations arm of the Food and Drug Administration, and the Internal Revenue Service.

Agents seized two packages, each containing 120 grams of fentanyl, documents stated. In November, investigators raided Shamo's Cottonwood Heights home and a second location in South Jordan, finding nearly 100,000 pills. Shamo reportedly ran one of his three pill presses at the time of the raid.

Some of the organization's customers ordered large quantities, indicating that they were subdistributors, said DEA District Agent in Charge Brian Besser.

In December, Shamo pleaded not guilty to running a drug operation. Crandall was arrested in Hawaii in May after conducting customer service for the organization while traveling abroad.

Fentanyl is 100 times more potent than morphine and 40 to 50 times more potent than street-level heroin, Besser said. Low production costs have motivated distributors to cut heroin with fentanyl or press the synthetic opioid into fake prescription drugs, he said, and users often don't know they're taking fentanyl.

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Steve Griffin | The Salt Lake Tribune U.S Attorney John Huber announces a federal grand jury indictment charging six people involved with an international drug trafficking organization involved in manufacturing fake prescription drugs made form Fentanyl. The announcement was made from the U.S. Attorney's office in Salt Lake City Wednesday May 31, 2017. Huber was joined by members from the DEA, Homeland Security, IRS, FDA and the U.S. Postal Service.