The probe to find out what led to Michael K. Williams's drug overdose finally reached a new development, authorities confirmed.

On Wednesday, police sources confirmed to Associated Press that four men believed to be members of the drug distribution crew who gave Williams fentanyl-laced heroin had been charged.

According to initial reports by U.S. Attorney Damian Williams and New York City Police Commissioner Keechant Sewell, four men were arrested on Tuesday and put in custody as part of the criminal complaints filed in Manhattan federal court.

The unsealed documents alleged that the men were involved in the distribution of drugs to Williams, which caused his death.

The Guardian noted that one of the men, Irvin Cartagena, was the one who sold the deadly substance to "The Wire" actor.

"Today, along with our law enforcement partners at the NYPD, we announce the arrests of members of a drug crew, including Irvin Cartagena, the man who we allege sold the deadly dose of drugs to Michael K Williams. This is a public health crisis. And it has to stop," attorney Sewell continued.

Michael K. Williams' Death Revisited

The first responders found William, who was then unconscious, in the dining room of his Brooklyn penthouse in September. His nephew found him before 2:00 p.m on Monday, calling cops after seeing an "unresponsive and cold" man. At 2:12 p.m, the responders pronounced him dead.

Soon after finding his body, they assumed that his cause of death was drug-related as they found heroin on his kitchen table. However, the police source clarified that no foul play was involved.

A representative of the late actor confirmed Williams' death in a statement to The Hollywood Reporter at that time.

READ ALSO: Actor Isaac Bardavid Cause of Death Heartbreaking: 'Wolverine' Voice Actor Dead At 91

"It is with deep sorrow that the family announces the passing of Emmy nominated actor Michael Kenneth Williams," spokesperson Marianna Shafran said. "They ask for your privacy while grieving this unsurmountable loss."

Meanwhile, New York City's medical examiner confirmed that he indeed died of acute drug intoxication after consuming drugs sold by a drug trafficking organization that has operated since at least August 2020.

Williams reportedly acquired the heroin laced with fentanyl on the day before his death. Despite the actor's death, the organization reportedly continued selling the same drugs in the neighborhood.

READ MORE: Tom Cruise Dating a British Woman After Failing to Win Angelina Jolie?