Diddy's ex-employee Rodney Jones is on the short list of accusers whose lawsuits might have sparked the federal investigation -- but he's not one of the witnesses the feds are interviewing ... not yet, anyway.

Sources with knowledge tell TMZ ... Rodney, AKA Lil Rod, is not one of the people federal prosecutors have called upon to provide sworn testimony for their investigation into the Bad Boy Records founder.

As TMZ previously reported ... Diddy's ex Cassie has been in touch with the authorities -- and is cooperating, alongside others who've made claims against the mogul.

Since Rodney is currently suing Diddy for sexual assault, he would presumably be one of the people the feds are interested in speaking with ... but we're told, at least so far, that's not the case.

Still, our sources say Rodney is willing to cooperate with the authorities if they choose to contact him ... but for the time being, we're told he's being patient and feels somewhat vindicated by the feds obtaining search warrants to raid 2 of Diddy's homes.

ICYMI ... after Diddy's L.A. and Miami homes were raided in March, Homeland Security revealed the searches were part of an ongoing sex trafficking investigation.

Diddy has yet to be charged with anything, and denies all the allegations ... but he is still facing a bunch of civil lawsuits -- several of which make sexual assault and sex trafficking claims similar to the ones put forth in Cassie's lawsuit.