LOS ANGELES (July 3, 2009)--A drug called Diprivan that is widely used in operating rooms to make people unconscious that’s seldom if ever prescribed for individual use has been found in the home of pop star Michael Jackson.

A registered nurse who had been working with Jackson had said he pleaded with her to give him Diprivan, because of his persistent insomnia.

Investigators are trying to determine if he was illegally provided with medications.

One expert says it’s not a drug he’d expect to find in a home.

“Diprivan, is the kind of drug used in hospitals, so doctors will not prescribe that medication for home use,” Dr. Lawrence Kobilinsky, the chairman of the Forensic Science Department at John Jay College, told CBS News.

The Los Angeles Police Department has asked the U.S. Drug Enforcement Administration to help in the investigation, The Associated Press reported.

Meanwhile, thousands of free tickets to a memorial service Tuesday morning in Los Angeles for the pop icon will be available through the Web site Staplescenter.com.

Saturday evening, names of people who registered will be randomly selected for the 11,000 seats inside Staples Center and for 6,500 seats in an adjacent theater, where a simulcast will be aired.