Three men arrested during the investigation into rapper Mac Miller's deadly overdose last year have now been charged with providing the drugs that killed him, U.S. prosecutors said Wednesday.

A grand jury indictment that was unsealed in Los Angeles accuses the men of conspiring and distributing cocaine and oxycodone pills laced with fentanyl that caused Miller's death in September 2018.

Cameron Pettit, Stephen Walter and Ryan Reavis were previously charged with drug-related offenses. Wednesday's charges add the allegation that their drugs led to Miller's death.

Miller, a Pittsburgh native, was discovered unresponsive in his Studio City home Sept. 7, 2018. The manner of death was certified as an accident, although it was later determined that the rapper died from an overdose of alcohol, cocaine and fentanyl.

Nearly a year later, Sept. 4, police arrested Pettit, 28, who allegedly supplied Miller with counterfeit oxycodone pills containing fentanyl.

Two weeks later, Sept. 25, police announced the arrest of Reavis, 36, in Lake Havasu, Arizona. At the time, police said Reavis was connected to Miller's death but would not say how.

The following day, police arrested Walter who is believed to be the source of the counterfeit drugs Petit sold to Miller.

The indictment alleges the men continued to distribute drugs through August 2019.

The Associated Press contributed to this report.