Jackson had many doctors, and ABC News has learned that as many as five may be under investigation. But so far, it seems Murray is the of the Los Angeles Police Department and federal Drug Enforcement Administration agents who are leading the probe.
And the investigation may not be his only problem.
ABC News has learned that the Murray is facing foreclosure. Documents obtained by ABC News' Primetime show that the doctor owes more than $15,000 in back payments from January for his Las Vegas home.
While investigators continue to build their case, Jackson's mother appears to be gearing up for a fight of her own.
Katherine Jackson Tuesday served the administrators of her son's estate with subpoenas seeking access to Jackson's contracts, including the "This Is It" tour agreement with AEG.
Administrators John Branca and John McLain said that it was Jackson himself who requested they control his estate, and that while they offered to share the contracts with his mother if she agreed to a confidentiality agreement, she has refused to those terms.
A hearing on control of Jackson's estate will be held next week.
Jackson's parents and siblings question Murray's role in Jackson's final hours, according to the Rev. Jesse Jackson, a longtime friend of the family. Rev. Jackson previously told ABC News that the family is suspicious.
The fact that the doctor had left the scene, was not available to sign the death certificate or answer the family's questions about their son's final moments did not sit right at all with the Jacksons, according to Rev. Jackson.
"When did the doctor come? What did he do? Did he inject him? If so, with what?" said Rev. Jackson. "Was he on the scene twice? Before and then reaction to? Did he use the Demerol? It's a very powerful drug. Was he injected once? Was he injected twice?"
Murray's lawyer Ed Chernoff, defending his client, has said that once Murray realized that CPR was not bringing Jackson back, Murray, he said, tried to dial 911 on his cell phone but did not have the exact address of Jackson's home. And with none of the phones in the home working "for privacy reasons," Murray ran around the house till he found Jackson's chef, who alerted security.
It was the security person, Chernoff said, who eventually dialed 911. CPR, he said, was done for 25 to 30 minutes before emergency officials arrived.
After Jackson's death, police officers towed a silver BMW from outside Jackson's Los Angeles home, which police confirmed belonged to Jackson's "personal physician" and which they believed contains evidence crucial to the investigation.
Law enforcement sources, however, confirmed to ABC News, that the car towed from Jackson's home is registered to one Susan Mary Rush. Rush is the sister of Dr. Conrad Robert Murray.
"The car was impounded," said Amanda Betat, a spokeswoman for the Los Angeles Police Department. "One reason it was impounded was because it may contain medication or evidence that could assist the coroner in determining the cause of death."
Megan Chuchmach contributed to this report.