BOSTON (AP) -- The Massachusetts medical examiner's office determined that cyanide poisoning killed an alleged extortion victim of Boston gangster James "Whitey" Bulger who had hoped to testify at Bulger's trial, prosecutors said Sunday. The medical examiner's office concluded that Stephen Rakes, 59, of Quincy, died of acute cyanide toxicity in July and ruled his death a homicide, according to MaryBeth Long, a spokeswoman for the Middlesex district attorney's office. Authorities said Rakes' death wasn't related to the Bulger case. Rakes' business associate, William Camuti, 69, of Sudbury, is charged with attempted murder and other crimes for allegedly poisoning Rakes' iced coffee. Camuti has pleaded not guilty. Prosecutors said Camuti owed Rakes money and lured him to a meeting where he poisoned his drink then drove Rakes around for hours before dumping his body. Long said the district attorney's office intends to file additional charges against Camuti based on the new findings by the medical examiner. A phone message for Camuti's attorney, Stanley Norkunas, was not immediately returned Sunday. Rakes' body was found in a wooded area of the Boston suburb of Lincoln on July 17, just a day after he learned he wouldn't be called as a witness against Bulger. Rakes openly despised Bulger and blamed him for seizing control of his South Boston liquor store to use as headquarters for Boston's Irish mob in 1984. Bulger was convicted in August of 11 killings and dozens of other gangland crimes. He is set to be sentenced next month.