How Medicated Was Michael Jackson?

The role of heavy pain-suppressant drugs in Michael Jackson's life — and possibly in his death — continues to come into focus ahead of Tuesday's planned memorial service, with new allegations on July 3 that the powerful anesthetic Diprivan was found in the pop star's home.

Citing a single unnamed law-enforcement source, the Associated Press made the Diprivan claim on Friday. Diprivan, also known as propofol, is typically used in hospital-operating theaters as an intravenous anesthetic. (Watch TIME's video "Appreciating Michael Jackson, the Musician.")

Dr. Drew Pinsky, host of Celebrity Rehab with Dr. Drew, says that even he was taken aback by the idea that Jackson or anyone else would receive Diprivan outside of a hospital-surgery situation. "I treat musicians all the time, and this is something even I have never heard of," Pinsky told TIME. "It's hard to get my head around. I'd have an easier time believing Martians set down outside of this building." (Read "Five Media Myths Debunked by Michael Jackson's Death."

"This is just not something used in the world outside of a hospital," Pinsky continued.

The AP report is just the latest in a series of allegations about Jackson's possible drug use. CNN's Dr. Sanjay Gupta cited sources from Jackson's 1996-97 HIStory tour who claimed that the singer had traveled with a "mini-clinic," which included an "IV pole, drips and what looked like a rack with lights and monitors." (See photographs of people around the world mourning Michael Jackson.)

One of Gupta's sources revealed that an anesthesiologist traveling with Jackson at the time had said, "I take him down at night, and I bring him back up in the morning."

Further, one of Jackson's recent nurses, Cherilyn Lee, has spoken out about repeatedly denying Jackson's specific request for Diprivan during the buildup to his ill-fated comeback tour. Pinsky says a civilian asking for this kind of drug specifically is "another bizarre, outlandish circumstance."

"I have never heard of a regular layperson understanding that it's even out there for them," Pinsky said.

While the world will not know exactly what role drugs played in Jackson's death until the autopsy results are released, observers expect further accounts of Jackson's alleged medicating to emerge in the days and weeks to come.

"This is just the surface still," Pinsky predicts gravely. "This is just the beginning."