Tupac's Family Lawyers Up Over Diddy Claim, Plans Legal Action If Evidence Surfaces

Tupac's family is clearly disturbed over an allegation that Diddy may have played a role in the late rapper's murder -- something they're now digging into with a new legal team, who plan to get to the bottom of it, and force action if they find any there-there ... TMZ has learned.

Sources with direct knowledge tell us members of Tupac's still-living relatives have retained attorneys Alex Spiro and Christopher Clore -- as well as a team of investigators -- to look into Keefe D's resurfaced allegation that Diddy offered to pay him and his crew money to take Pac out in the '90s.

You'll recall ... this claim -- which, thus far, is unsubstantiated -- came to light anew last week when prosecutors in Keefe D's murder case included an old transcript from an interview he did in '09, where he alleged Diddy was willing to pay up to $1 million for a hit on Tupac.

Diddy was never charged over that claim, and we've even heard cops in Vegas never took Keefe's claim to be legit -- however, Tupac's family clearly wants this vetted thoroughly.

We're told the family feels there might be something to this claim, and with the legal team they've brought on -- they're hoping to dig up any potential evidence that exists to corroborate it ... as Spiro and Clore plan to run down any and all leads they can find.

Our sources say the Diddy allegation will be the main focus of this private investigation -- and we're told the team is confident they'll surface potential evidence, including more legal docs.

If they do ... we're told any material that implicates Diddy in alleged wrongdoing will be passed on to the proper authorities to be looked into for possible criminal charges -- and we should say, there's no statute of limitations on murder.

If nothing comes about on the criminal front ... we're told Tupac's family would potentially look into filing a wrongful death suit -- again, assuming they uncover evidence to do so.

Worth noting ... Diddy has explicitly denied any involvement in Tupac's murder a handful of times over the years -- and he's never been arrested as it pertains to this years-old rumor. Nonetheless ... Tupac's family wants to clear the air on this once and for all.