Jackson's parents and siblings are questioning 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 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?"
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."
Law enforcement sources told ABC News Jackson was addicted to Oxycontin and received it and Demerol in daily doses.
Jackson's brother Jermaine has said that the singer's doctor had tried to resuscitate him.
"His personal physician, who was with him at the time, attempted to resuscitate my brother, as did the paramedics who transported him to Ronald Reagan UCLA Medical Center," Jermaine Jackson said in the announcement that confirmed Michael Jackson, 50, had died.
Before authorities confirmed to ABC News that Murray was being sought for an interview, speculation swirled as to who might be the "personal physician" who was with Jackson at the time of his death.
Murray personally has been taken to civil court in Clark County twice in the past year by Capital One Bank for unpaid bills of around $2,000 in total.
The LAPD said it knew Jackson had several doctors.
For years, Jackson has been treated by Dr. Arnie Klein, a dermatologist. It was in Klein's office that Jackson met Debbie Rowe, the mother of his first two children. A housekeeper at Klein's homes said the doctor was "out of town."
Megan Chuchmach contributed to this report.