A prison inmate coordinated a methamphetamine ring that involved at least two Indiana prisons using cellphones and drugs smuggled in by guards, according to a federal indictment unsealed Wednesday that charges 40 people in connection to the scheme.

At least three inmates are among those charged, including the alleged ringleader, Oscar Perez, who's serving time for murder and attempted murder. At least 17 people appeared in court Wednesday in Indianapolis after about 300 FBI agents fanned out across the state and made arrests.

Prosecutors said the defendants were flight risks, and the judge ordered them to remain in custody.

The activity, which also included heroin trafficking, occurred at the Westville Correction Facility in northern Indiana and the Wabash Valley Correction Facility in southwestern Indiana, according to the indictment.

Court documents allege that one corrections officer, Jon Dobbins, was found "in possession" of nearly 21 grams of a mixture and substance containing meth, and had a cellphone that he was going to "clandestinely bring" into the prison and leave with an inmate.

Dobbins didn't have a listed phone number in Indiana, according to phone records. The indictment refers to multiple prison guards being involved.

The Indiana Department of Correction issued a statement saying it has been cooperating with the FBI since the investigation began and that that department uncovered the evidence that identified and led to the state criminal charges against Dobbins.