Anne Heche's horrific crash into a California home now has the potential to land the actress into even deeper legal trouble ... she's now under investigation for felony DUI.
LAPD sources tell TMZ ... they've now upped the investigation to a felony because the woman inside the home Anne barreled through with her Mini Cooper claims she was injured -- suffering cuts requiring medical treatment.
Cops believe Anne was driving under the influence of drugs and/or alcohol ... because she was driving erratically and recklessly, hitting a garage and a parked car before slamming into the home.
Cops also took note of a photo of Anne in the car just before the crash, with what appeared to be a bottle of alcohol in a cup holder.
Anne's rep says the actress is still fighting for her life ... she lost consciousness shortly after the crash, and has been in a coma ever since.
TMZ broke the story, Anne almost struck a woman before hitting another vehicle and crashing into a garage in the moments leading up to the fiery explosion.
Heche was pulled from her car as it burned and loaded onto a stretcher by paramedics. The vehicle was left a smoldering pile of metal.