They're suspected of running parallel methamphetamine and fentanyl distribution conspiracies in northern Minnesota.
All three inmates survived.
The pills could contain dangerous amounts of fentanyl, which is often to blame in fatal overdoses.
The arrest was made nearly one month after the 23-year-old's death.
One man died, one man is in the ICU and another was injured.
She died from a mixture of fentanyl and alcohol toxicity.
Two people have been arrested in connection with the haul.
Police suspect the substance may have been laced with fentanyl.
He's charged with distributing the drug throughout the U.S.
The pills appear like legal oxycodone, but contain the deadly synthetic opioid.