The cause of death of a victim of Boston mob boss Whitey Bulger was ruled a homicide by cyanide poisoning, CNN reported.

MaryBeth Long, a spokeswoman for the Middlesex District Attorney's Office, announced that the Massachusetts Medical Examiner's Office recently declared the cause of death for Stephen Rakes, a business associate of William Camuti, who has already been charged with attempted murder, misleading police, and unlawful disposition of human remains.

Camuti, 69, confessed to putting potassium cyanide in an iced coffee he gave to Rakes, 59, at a McDonalds in Waltham, according to testimony from a Massachusetts state trooper at a hearing in Concord District Court on Sept. 10.

"He indicated that he had purchased two iced coffees. He did in fact purchase potassium cyanide, which had been delivered and stored," said Trooper Michael Banks.

Rakes only took one sip of the drink before saying it was too bitter to finish. Camuti then drove him around in different towns before he "succumbed to ... ingesting" the poison, Banks testified.

He allegedly lured Rakes to meet him after calling him about a potential investment opportunity in Wilmington. That same day, on Jul. 16, Rakes was seen leaving a federal courthouse where he regularly attended Bulger's trial.

The following day, his remains were found in a wooded area wearing the same clothes.

He reportedly poisoned Rakes at a time where Camuti owed him money.

Long said Camuti is being held without bail for 90 days after the judge said his release would not "reasonably assure the safety of any other person or community."

According to the Centers for Disease Control and Prevention, potassium cyanide obstructs the body's ability to use oxygen, making exposure to it rapidly fatal.

In August, Bulger was convicted of 31 of 32 counts, including extortion, money laundering, drug dealing, and weapons possession. A federal jury also found Bulger responsible for the murders of 11 people.