Adria English's attorney Ariel Mitchell-Kidd joined us on "TMZ Live" Wednesday and told us a possible criminal indictment against the Bad Boy founder is coming sooner than later, and perhaps even "very shortly."

Mitchell-Kidd is definitely in the know here ... her client is the former porn star who recently filed a bombshell lawsuit accusing Diddy of sexual assault and sex trafficking.

Adria's lawsuit is among several accusing Diddy of sexual assault, human trafficking and other serious offenses ... including the one he settled with Cassie, which mentioned the now-infamous video of him brutally beating her in a hotel hallway.

There's been a possible federal indictment looming in the background for a few months now ... in May there were reports a grand jury had been empaneled to hear evidence in his federal probe, indicating Diddy could face a possible criminal indictment.

Mitchell-Kidd says Adria came in at the tail end of the federal investigation, and she says the finish line is coming up.

Diddy's been popping up more recently ... he's been seen boarding his private jet and going white water rafting in Wyoming, visuals that drew the ire of Mitchell-Kidd and Cassie's attorney, who blasted Diddy for coming off as unremorseful for his alleged crimes.

Mitchell-Kidd adds to that here ... telling us it feels like Diddy is checking off some bucket list items because he knows the walls are closing in and the indictment is waiting in the wings.

It's an interesting conversation ... and it sounds like Mitchell-Kidd will have more to say on Diddy when and if the indictment drops.