Michael Jackson's Arms Marred by Track Marks Consistent with Potent Sedative Use

Both of pop superstar Michael Jackson's arms were scarred with track marks, investigators probing his death say, and the marks are consistent with the finding of the potent sedative propofol (trade name Diprivan) in his home -- a drug that is increasingly at the center of their probe into what caused Jackson's death, ABC News has learned.

According to sources involved in the death investigation, several Hollywood and Beverly Hills doctors are now part of the investigation.

The probe is being led by the Los Angeles Police Department in cooperation with the Drug Enforcement Administration. The California Department of Justice has offered technical support in terms of its powerful searchable data base of patient information that includes drugs, doses, the doctors that administered them and the patients that received them.

Follow ABC News Television's live coverage anchored by Charlie Gibson at 1 p.m. ET.

Prescription medications were found inside Jackson 's $100,000 per month rental home that included ones in his name and ones in other names, including ones that appeared to investigators to be aliases. The medications had been prescribed by multiple doctors.

Jackson was addicted to the analgesic Demerol and to Oxycontin, investigators have told ABC News, and took the drugs daily. Medical experts have reported propofol "blocks out the world."

Those addicted to it routinely report that their abuse began with using the drug to treat insomnia -- an ongoing problem for Jackson.

Medical experts point out that the abuse of Demerol could have set the stage for cardiac arrest, by increasing Jackson 's risk.

One pharmacologist blogged about Propofol this week and explained in his science blog how Demerol abuse could have caused cardiac problems and could have increased his risk for heart rhythm disturbances from the Propofol: "As I wrote last week in my blog post on Demerol ® (meperidine), Jackson's reported long-term use of this analgesic for back pain may have already primed him for cardiac problems due to the accumulation of a toxic metabolite, normeperidine," Dr. David Kroll said. "However, most relevant to the Jackson case is that propofol can cause cardiac tachyarrhythmias (rhythmic disturbances at high heart rate), especially in people predisposed to cardiac problems."

Drugs Found in Michael Jackson's Home

Medical experts contacted by the ABC News Medical Unit said that the list of 20 drugs reportedly found in Jackson's rented home was "jaw-dropping" and "amazing."

"That list is enough to put down a swarm of zombies," said Richard Bradley, Chief, Division of EMS and Disaster Medicine at the University of Texas Health Science Center at Houston.

"The list …would be typical for an anesthesia cart in an operating room or what you might find in a recovery room, ICU, ED, etc.. Definitely not what you'd expect to find in a home," said Joseph Ornato, Chair of the Department of Medicine at Virginia Commonwealth University.

ABC News has reported on a number of those drugs including Demerol and Oxycontin, which the experts note are "cousins to morphine."

All of the following drugs reportedly found in Jackson's home are in that same category of opioid narcotics found in Jackson's home: methadone, Fentanyl, Percocet, Dilaudid and Vicodin. Generally prescribed as painkillers, the drugs are similar in mechanism -- taking a combination of these medications is like overdosing on one drug alone.

"Any of these can kill," said Marcel Casavant, Chief of Pharmacology/Toxicology at Ohio State. "Usually [they kill] by stopping breathing and lowering blood pressure, so the heart and the brain don't get oxygen."

The stash of drugs raises ethical questions about any physician or physicians involved in prescribing and administering them.

"There is a very high standard for appropriate use of narcotics and Mr. Jackson's doctors are required to follow that standard. If not, then the care they provided is negligent," said Lloyd Saberski, Medical Director, Advanced Diagnostic Pain Treatment Centers at Yale University.

Medical Experts Weigh In

Medical experts consulted by ABC News cautioned that the track marks could not by themselves conclusively suggest Jackson abused propofol.

"Given the list of medications that were reported to be found [in Jackson's home], it may be difficult to qualify these as purely propofol-induced track marks," said Lina Matta, Clinical Pharmacy Practice Manager at Brigham and Women's Hospital.

Those contacted said that while the track marks may be attributable to propofol, it's impossible to know that just from the marks themselves. They could have come from abuse of other drugs.

The Sun has reported there were at least 20 drugs found in Jackson's home, and many of these can be injected, including Methadone, Fentanyl, Demerol, Versed, and Lidocaine.

Propofol is a serious general anesthetic that should only be administered by a trained professional because it can cause the patient to stop breathing, even when used correctly, according to medical experts.

"Propofol at doses used in operating rooms causes the cessation of breathing in 8-30 plus percent of patients at the initiation of anesthesia," said Joseph Tobin, Chairman of the Department of Anesthesiology at Wake Forest University Baptist Medical Center.

Hospitals like it because it is short-acting. If a patient is having a brief procedure, they do not have to be knocked out for a long period of time. Recovery is quicker. But while the patient is under propofol, he or she must be continually monitored.

"Propofol is mind boggling that [Jackson] would have that in the home," said Chris Cannon, a cardiologist at Brigham and Women's Hospital. "It is used for short term anesthesia for procedures... For this however, we have an anesthesiologist (actually 2) at the bedside monitoring [heart rate, blood pressure] breathing, airway competency, careful dose monitoring etc"

Cindy Kuhn, Professor of Pharmacology and Cancer Biology at Duke University Medical Center further explains: "The difference between a dose that is sedating and one that can be lethal is very small - you would want to have the ability to support breathing (with a respirator for example) in case of overdose- that is why it would not be used outside of a hospital. This drug could be lethal on its own - it would slow breathing to the point that it stopped…"

Indeed, just last year, researchers published the first known report of a murder due to propofol. A 24-year old nurse in Gainesville, Florida, was killed by an overdose of propofol. A male nurse acquaintance was convicted of the crime.

"Propofol has no place in a household," agreed Lloyd Saberski, Medical Director at the Advanced Diagnostic Pain Treatment Centers at Yale University. "This alone is a deviation and many laws were likely violated just to get the Propofol there."

JoAnna Schaffhausen contributed to this report.

Click Here for the Blotter Homepage.