Mobster Anthony "Tony Pro" Provenzano, the man former Teamsters leader Jimmy Hoffa was on his way to meet when he vanished, has died of a heart attack while serving a federal racketeering sentence.

Provenzano died at Lompoc District Hospital, near the federal prison where he was serving a 20-year term for two racketeering conspiracy offenses, prison spokesman Chuck LaRoe said.The 71-year-old former New Jersey union boss had been confined to the hospital in Lompoc, 140 miles northwest of Los Angeles, for treatment of congestive heart failure.

A convicted murderer and extortionist, Provenzano engendered strong loyalty in Teamsters Local 560 in Union City, N.J. It was the nation's third-largest local with 13,000 members when he ruled it in the early 1960s.