Michael Jackson Investigation Zeroing in on Conrad Murray

The central target in the investigation into Michael Jackson's death is Dr. Conrad Murray, who was at Jackson's house when the singer went into cardiac arrest.

According to TMZ, the doctor is not cooperating with authorities, but they have still uncovered evidence linking him to the drug that may have killed Jackson.

As a result of Dr. Murray's second interview with police, the LAPD obtained a warrant to conduct a second search of Michael's home, and they found Propofol.

This powerful anesthesia should never be found or used outside a hospital. There is evidence Propofol was given to Jackson before his heart stopped beating.

There is also evidence Dr. Conrad Murray may have administered it.

Murray's lawyer, Ed Chernoff, would neither confirm nor deny if Dr. Murray administered Propofol to Jackson. Law enforcement sources tell TMZ if they conclude the doctor administered the drug, it may lead to manslaughter charges.

Investigators are also suspicious of the delay between Jackson succumbing to cardiac arrest and the ensuing 911 call, during which he was already unconscious. Murray says he waited 20-30 minutes because he didn't know the music icon's address.

Not only was Murray serving as Jackson's personal physician, but MJ lived on one of the most famous streets in the world - one house above Sunset Boulevard.

The investigation into Jackson's death has also fueled an investigation into his history with drug use and the doctors who may have enabled his habits.

Law enforcement is seriously investigating the prescription practices of several doctors who gave Michael Jackson access to various medications.

Investigators are particularly interested in doctors who used aliases to write prescriptions for Jackson. One of the central figures: Dr. Arnold Klein.