(CNN) -- Images of a sky-blue car, its windows shattered by bullets, took center stage Monday at the trial of reputed mob boss James "Whitey" Bulger. Bulger's onetime crime partner Kevin Weeks testified he was there the night Edward "Brian" Halloran was killed. He placed the gun squarely in Bulger's hands. "Jim Bulger just kept shooting," said Weeks describing Halloran's writhing, bullet-ridden body as "bouncing off the ground." Halloran is one of 19 people Bulger is accused of killing during his 20-year reign of terror in South Boston. Bulger is on trial in federal court in Boston. Rogue FBI agents had alerted Bulger that Halloran was going to cooperate against Bulger in a couple of killings.
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Kevin Weeks, ex-partner of reputed mob boss James "Whitey" Bulger, testifies
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Bulger "just kept shooting" Brian Halloran in a May 1982 homicide, Weeks says
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Weeks radioed Halloran's movements to Bulger before the shooting, he says
As he began to make his way out of the club, Weeks radioed Bulger, referring to @placeholder as "balloon head," a nickname they used because "Halloran's head was so big."