Whitney Houston’s family was told by L.A. County Coroner officials … the singer did not die from drowning, but rather from what appears to be a combination of Xanax and other prescription drugs  mixed with alcohol … this according to family sources.

No illegal drugs have been found in the hotel room where Whitney Houston died — at least not yet — but prescription drugs were present, and it’s possible the singer drowned in the bathtub … TMZ has learned.

Some DAILY FIX updates:

Update #5: Fox TV celebrity journalist Flo Anthony says it was Houston’s brother Michael who found her dead in the bathtub and not Ray J.

Update #4: The Beverly Hilton Hotel Staff has told TMZ that Whitney “partied heavily” last night at the hotel with a group of friends. Apparently Whitney and her friends were in the bar for a long time and the group was drinking and very loud.

Update #3: The video [below] shows Whitney Houston’s last performance. She performed briefly with R&B singer Kelly Price on Thursday night at a Grammy party at Tru Hollywood.