5/30/2013 8:30 PM PDT

Arrest in Soulja Boy Hit-and-Run

Cops have arrested a man in connection with the mysterious hit-and-run involving Soulja Boy's Bentley.  TMZ has learned ... a rapper was busted, but it wasn't Soulja.

TMZ broke the story ... a man was seriously injured January 9 in Hollywood after colliding with a Bentley that was making an illegal turn.  After some crack investigating by the motorcyclist's friend, cops got wind that the phantom car may have belonged to Soulja Boy.

Cops then checked a secret network of cameras that take photos around L.A. and capture cars on the road.  They punched in the license plate number of the Bentley and found multiple pics of the car with damage that corresponded to the accident.  But they did not have pics capturing the accident.

Police have arrested Abrahim Mustafa ... we're told he's one of Soulja Boy's hangers-on.  He's a rapper who goes by Arab.  He's been arrested for felony hit-and-run.

We're told cops still want to speak to Soulja Boy.