EXCLUSIVE

Law enforcement sources tell us ... the woman who filed the report claims she was hanging out at Bieber's home around 3:30 AM Thursday morning -- Bieber was NOT there btw -- when she decided it was time to leave.
But as she tried to exit the mansion, the woman claims Twist grabbed her by the arm in a forceful manner -- and tried to prevent her from leaving the home.
We're told the woman drove straight from JB's home to a nearby Sheriff's Department.
Sources say cops are investigating the allegation.
It's not the first time JB's sidekick has been accused of wrongdoing -- just last month, Twist was arrested for DUI while driving Bieber's famous Fisker Karma.
Story developing ...
