"Gimme that ring."
The Bold Gangster worked for Winn Farrow. He was associated with the murder of Press Tilton and the attempted double-murder of Bobby Pendragon and Vo Spader. He was the bravest of the two gangsters who confronted Bobby and Spader in the subway, and was also the apparent leader.
He demanded to have Bobby's Traveler ring for proof that they had found them. This was probably needed because of Winn Farrow's violent nature. He may have killed the two if they had no proof of the slaying.
Fellow gangsters probably disposed of his body with lack of respect. They might have burned it or dumped it in a nearby body of water.