A letter, claiming to be from convict Dexter Isaac, was posted on music website AllHipHop.com and suggested he was paid to accost the hip-hop star outside the Big Apple's Quad Studios.
The letter also suggested the author had knowledge of who was responsible for Shakur's fatal 1996 shooting, which remains unsolved.
A New York Police Department (NYPD) representative has confirmed they are investigating whether the post is legitimate and plan to talk to the named convict.
Spokesman Paul Browne tells the New York Post, "NYPD detectives plan to interview the prisoner."
The letter also mentions James 'Jimmy Henchman' Rosemond, and his lawyer, Jeffrey Lichtman, has now spoken out to blast allegations his client paid to have Shakur robbed.
He says, "Where was he the last 17 years (with this version of events)?..." adding the allegations are "c**p."
Tagged in Tupac Shakur