BOSTON — A former FBI agent has testified that a man who was allegedly killed by James "Whitey" Bulger predicted his own death if Bulger was to learn he'd been cooperating with the FBI.

Retired agent Gerald Montanari told jurors Monday that Edward "Brian" Halloran had agreed to testify against Bulger and members of his gang, hoping he could get help on a murder charge he faced.

Montanari says Halloran told him that if Bulger or his partner found out he was cooperating, they would "go to any extreme," even if it meant killing bystanders.

Bulger is charged with opening fire on a car Halloran was in after learning Halloran was talking to the FBI. Halloran and Michael Donahue, an acquaintance, were killed.

Tom Donahue said his dad’s death certificate, which lists multiple gunshot wounds as a cause of death, should also list the names of gangsters and FBI agents who sealed his father’s fate.

The state’s former chief medical examiner testified on Michael Donahue’s certificate and 18 others, for each of the 19 people Bulger allegedly killed.

“I bring my father’s death certificate with me every single day, so actually going over it and hearing it, you know obviously it was horrible, but I knew every word that was on there before he was even saying it anyways,” said Tom Donahue.

Michael Donahue died in a hail of gunfire from automatic weapons as he gave Halloran a ride in 1982. Halloran had more than 20 wounds caused by 14 bullets, none hit vital organs, but he died of blood loss.

“Whitey was trying to prove a point and sit there and make him suffer in broad daylight,” said Tom Donahue.

The government said Halloran was murdered because he was ready to testify against Bulger and the gang about the murder of World Jai Alai owner, Roger Wheeler, in Tulsa, Okla.

Bulger has pleaded not guilty to participating in 19 killings.

Bulger’s former partner, Stephen "The Rifleman" Flemmi, is expected to take the stand Wednesday or Thursday.

The Associated Press contributed to this report.

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