EXCLUSIVE: Source - Involuntary Manslaughter Most Likely Charge Against Michael Jackson's Doctor

Dr. Conrad Murray will face an involuntary manslaughter charge if he is prosecuted in the death of pop superstar Michael Jackson, a source close to the investigation told RadarOnline.com exclusively.

And, as RadarOnline.com reported previously, the Los Angeles District Attorney will get the first shot at prosecuting Murray even though the Drug Enforcement Agency and the California Attorney General are also involved in the investigation.

Murray could face several different charges but the investigation is tracking toward involuntary manslaughter. The decision to charge Murray has not yet been made, the source said.

A search warrant was served on Murray's office in Houston last week. Murray was staying with Jackson five days a week, a source told RadarOnline.com, and Murray performed CPR on the singer before 911 was called the day he died.

Jackson's drug intake is a key element of the investigation and propofol, a powerful anesthetic, was found at his home. Jackson had sleep issues and several reports say he turned to propofol. The drug is always administered with oxygen and RadarOnline.com was first to report that Jackson's chef saw Murray carting large oxygen tanks around the house.

Asked if he administered propofol to Jackson, Murray has refused comment to RadarOnline.com. Under the California Penal Code, section 192(b) involuntary manslaughter is defined as, "Involuntary--in the commission of an unlawful act, not amounting to felony; or in the commission of a lawful act which might produce death, in an unlawful manner, or without due caution and circumspection," i.e., disregard for human life.