Updated

Police and the FBI are searching for two young Detroit siblings after their 27-year-old mother was found shot to death in a vacant house about six miles from her home.

The Wayne County medical examiner's office says an autopsy Tuesday determined Alicia Fox had been shot twice in the head. Her body was badly decomposed.

Detroit police spokesman Officer Adam Madera says Fox had been missing for several weeks. A family member found her body Monday night in the basement of the abandoned house after getting a tip from an "unknown person."

Neighbors said they last saw Fox and her children around Memorial Day at their home in northwest Detroit.

Still missing are 6-year-old Kaylah Hunter and 6-month-old brother, Kristian Justice.

No suspects have been identified.