Police are investigating a possible break-in at Miley Cyrus' home in the Valley AGAIN ... TMZ has learned.
Law enforcement sources tell us Miley's assistant came home around midnight Saturday/Sunday morning when she noticed things were not in the right place -- so she called cops.
We're told once again there was no sign of forced entry ... so officers will review Miley's security footage to look for any clues. A fingerprint unit is also on the way to her house.
Miley was not home at the time.