An alleged extortion victim of Boston gangster James "Whitey" Bulger, who was found dead while Bulger was on trial, died from cyanide poisoning, officials said on Sunday.
Stephen Rakes, 59, had wanted to testify at Bulger's trial that the mob boss had forced him at gunpoint to sell a liquor store for pennies on the dollar.
His body was found in July in Lincoln, with no obvious signs of trauma.
Authorities said in the summer that his death was not related to the case against Bulger, who was found guilty in August of murder and racketeering.
The Massachusetts Office of the Chief Medical Examiner found that Rakes, of Quincy, was killed by acute cyanide toxicity, said a spokeswoman for the Middlesex District Attorney's Office.
The death was ruled a homicide, the spokeswoman said.
One of Rakes's business associates, 69-year-old William Camuti of Sudbury, was arrested in August on charges that he gave Rakes a coffee laced with cyanide.
Prosecutors have said that they believe Camuti acted alone.
The District Attorney's Office said on Sunday that it would seek additional charges.