Whoever made off with the $100,000 worth of jewelry and purses from Miley Cyrus' house last month did it from the inside ... at least that's what law enforcement believes.
Our cop sources tell us ... they've looked at various surveillance videos from Miley's home and the homes of neighbors ... and there's no sign of anyone suspicious entering or leaving her house.
What's more ... there's no sign of forced entry.
We're told multiple people had access to Miley's home ... especially since there were a number of workers at the house and cops are now scrutinizing them.
Miley wasn't home at the time the stuff was stolen.