Whitney Houston's Cocaine Subject of Police Investigation
03/23/2012 AT 03:15 PM EDT
The singer died by drowning in the bathtub of her Beverly Hilton Hotel suite, according to the coroner, but it was also determined that a non-lethal level of cocaine was found in her body, and that long-term cocaine abuse contributed to her death.
So far left unanswered is whether any illegal drugs were found at the scene, whether anybody from Houston's entourage is suspected of cleaning up the area before paramedics arrived, and how Houston obtained the drugs.
"It's still an open investigation for us," Beverly Hills Police Lt. Mark Rosen told PEOPLE when asked if cocaine was found in the hotel room. "I can’t disclose any details about the investigation."
Coroner Assistant Chief Ed Winter previously confirmed that prescription bottles were found at the scene but that the medications were "not in an alarming amount." The coroner has not commented on whether illegal drugs were also found.
Houston, 48, was found unresponsive and underwater in the tub on Feb. 11, a day before the Grammy Awards, and was pronounced dead at the scene soon afterward.
Houston had a long and well-publicized battle with substance abuse and went into rehab several times, including a stint in May 2011 in an outpatient program for what her reps said was drug and alcohol treatment.
The coroner's office on Thursday released only a brief synopsis of its findings. A full autopsy report, which typically includes details of what investigators find at the death scene and witness interviews, is expected in about two weeks.
What the coroner is announcing is that based on a Feb. 12 autopsy and toxicology tests, "The final cause of death has been determined to be drowning (and) effects of atherosclerotic heart disease and cocaine use."
Cocaine, according to the report, was "contributory to death." Also found in her system were marijuana, Xanax, the muscle relaxant Flexeril and Benadryl, "but did not contribute to the death."
The bottom line, according to the report: "No trauma or foul play is suspected."
Additional reporting by KEN LEE