OXFORD, Miss. (AP) — A leader of a nationwide prison gang operating in the Mississippi prisons was sentenced Thursday to 20 years behind bars for a racketeering conspiracy conviction, federal prosecutors announced.

Allen Posey, 49, of Hazlehurst, Mississippi, oversaw the criminal activities of the Simon City Royals gang operating in the Mississippi Department of Corrections system, but with members and associates acting on their behalf outside of prisons in Mississippi, Louisiana and beyond, federal prosecutors said.

Posey personally ordered the killings of rival gang leaders and was involved in drug trafficking and money laundering, according to a news release from the U.S. Attorney’s Office for the Northern District of Mississippi, citing court documents. It did not elaborate on those targeted for death.

The gang engaged in widespread drug trafficking, including smuggling large quantities of methamphetamine, marijuana and other drugs into dozens of Mississippi state prison facilities, the news release said.

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Posey pleaded guilty in the case in early October. At Thursday’s sentencing hearing, U.S. District Judge Michael P. Mills called the gang a “diabolical organization” and sentenced Posey to 20 years in prison followed by five years of supervised release.

“This defendant was responsible for countless crimes, and now he will spend functionally the rest of his life in prison,” said U.S. Attorney Clay Joyner. “Safeguarding our communities from violent gangs will always be a top priority for our office.”

In a separate case, Mills sentenced another gang member, Dillon Heffker, 33, of New Orleans, to 35 years on the same charges, federal authorities said.

Heffker stabbed a subordinate Simon City Royals gang member to death at Wilkinson County Correctional and was involved in drug trafficking and money laundering, according to court records. An investigation found that the gang paid Heffker and another gang member for the killing, authorities said in a news release.

Heffker pleaded guilty in the case on Oct. 5.

“Several years ago, the Simon City Royals, a violent criminal gang, were the driving force behind an explosion of violence in Mississippi prisons,” Joyner said. “Today’s sentence, as well as the almost 50 other recent prosecutions of the gang and its affiliates, should send a clear message that we will use every tool at our disposal to prosecute those who commit such heinous acts from behind bars or elsewhere.”