Booking mug handout of former mob boss and fugitive James "Whitey" Bulger, who was arrested in Santa Monica

A body found near Lincoln, Mass., has been identified as  Stephen “Stippo” Rakes, who was to be a key  witness in the trial of notorious South Boston gangster James “Whitey” Bulger.

Rakes was scheduled to testify that he was forced at gunpoint to turn over his liquor store to Bulger 29 years ago.

A law enforcement official confirming Rakes death to USA TODAY says authorities are investigating that he may have died of natural causes. The body of Rakes, 59, was found Wednesday afternoon.

The official said there is “no obvious sign” that he was murdered. ABC News reported that police told  Rakes’ family that the death appeared to be a suicide. No phone or wallet was found on the body.

A close friend of Rakes, Steve Davis, tells ABC News, however, that he would not have killed himself and “was looking forward to taking the stand.” Davis said Rakes had planned to deliver a “big bombshell” on the witness stand.

Rakes has been attending Bulger’s federal racketeering trial in South Boston regularly over the past six weeks.

ABC says that Rakes was a particularly angry and determined victim of Bulger’s gangland tactics.

He was apparently supposed to testify that Bulger, 83, a member of his Winter Hill gang, Stephen “The Rifleman” Flemmi,  threatened his daughter at gunpoint and forced him to turn over his South Boston liquor store. The building later became Bulger’s headquarters.

Bulger, a much-feared South Boston gangster for decades, fled the city in 1994 ahead of his arrest. He was captured in California two years ago after 16 years on the run.

Bulger has pleaded not guilty to 48 charges, including 19 counts of murder, extortion, money laundering, obstruction of justice, perjury, narcotics distribution, and weapons violations.