A sedative used in operating rooms which makes people unconscious, was found at the house of Michael Jackson, a law enforcement official said Friday, according to the Associated Press.

The sedative - administered intravenously - is called Diprivan and is also known as Propofol. It is rare to have it in a private home, the agency reported citing the official.

According to Cherilyn Lee, a nurse that worked with Jackson, the singer was pleading for Diprivan because a persistent insomnia he faced in the midst of rehearsals for his planned This is it tour in London.

Lee said she rejected his demands because the drug was unsafe.

Jackson died at age 50 after suffering a cardiac arrest at his home in Los Angeles. The cause of his death is being investigated and authorities are probing into allegations that the pop singer consumed painkillers, sedatives and antidepressants.

Michael Jackson's public memorial service will be held at the Staples Center in Los Angeles and free tickets will be distributed randomly to people who begin registering on Friday July 3 from 1:00 p.m. EST to Saturday July 4, 9:000 p.m. EST on the Staples Center website.