Law enforcement sources tell TMZ the LAPD has asked the DEA to assist them in its investigation into multiple doctors who treated and prescribed medications for Michael Jackson.

The LAPD wants help in tracking down the source of medications. As we first reported, the powerful anesthesia Propofol was found in Jackson's home and it appears he got the drug through an IV before he died.

As we first reported, Propofol, a powerful anesthesia, was found in the house after Jackson died. Various medical experts tell us there is absolutely no medical justification for Jackson to have had this drug in his home -- it is used to knock people out before surgery. It is administered through an IV.

We're told Jackson wanted the drug to sleep and that he had cravings for anesthesia -- whenever he had even the most minor medical procedure ... he had the doctor put him under.

It is increasingly looking like Propofol may have caused Jackson to go into cardiac arrest and die.