A witness in the murder trial of reputed Boston mob boss James "Whitey" Bulger was able to tie Bulger to a murder when former hit man John Martorano testified that Bulger assisted in the 1974 killing of Alfred "Indian Al" Notarangeli, reports the Boston Globe.

Martorano testified that he shot Notarangeli from his car while Bulger followed in a second car to ensure that the killing went as planned. Bulger is charged with 19 murders conducted between the years of 1972 to 2000 while running the Winter Hill Gang.

In addition to linking Bulger to the killing Martorano recalled Bulger telling him about a conversation between William Bulger, a politician and brother of the accused, and Federal Bureau of Investigation agent John Connolly who is currently in prison for helping James Bulger. Connolly allegedly told William Bulger, "If there is anything I can do for you, let me know." William Bulger responded by asking Connolly to keep his brother out of trouble, according to the Boston Globe.

When Martorano learned that Bulger and fellow Winter Hill Gang member Stephen Flemmi had become FBI agents it crushed him. Martorano had named his son James Stephen in honor of his two fellow gangsters and friends, according to Reuters.

"After I heard that they were informants, it sort of broke my heart," Martorano said. "It broke all trust that we had, all loyalties, and I was just beside myself. They were my partners in crime, my best friends, my children's godfathers."

Despite extensive files that the FBI claims is information given to them by Bulger over the year the former mob boss denies being an informant.

Bulger's attorney, J.W. Carney has attacked the credibility of Martorano's testimony citing "unbelievable incentives" given to him in exchange for his testimony against Bulger. Martorano has admitted to killing 20 people while part of the Winter Hill Gang, yet he only served 12 years in prison for his crimes, according to the New York Daily News.

While on the stand prosecutors read aloud 10 names to Martorano asking if he had killed the men, Martorano answered yes to each.

While addressing the jury Carney attempted to paint Martorano as a madman and a "criminal psychopath," according to ABC News.

"He would kill people almost randomly as the mood befit him," Carney said. "He would kill people because they crossed him. He would kill people because he wanted to get their money. He would kill people easily as we would order a cup of coffee."