Michael Jackson
Michael Jackson (C) is aided by bodyguards as he arrives more than an hour late with his father Joe Jackson (R) for his child molestation trial at Santa Barbara County Superior Court on March 10, 2005, in Santa Maria, California. Reuters

Michael Jackson, who would have been 55 on Thursday had he not died of a drug overdose on June 25, 2009, was heavily dependent on propofol, a drug he used to treat his insomnia for at least a decade before his death, Christine Quinn, a doctor, said on Wednesday, according to Associated Press.

Quinn was testifying in the negligent-hiring lawsuit filed by Jackson's family against AEG Live LLC -- the promoters in charge of Jackson’s come-back concerts. While Jackson’s family argue that the company was negligent in hiring Conrad Murray, Jackson's personal physician at the time of his death, AEG is trying to prove that it had no knowledge of the treatments Jackson was receiving, and hence it is not responsible for the singer’s death.

Testifying for the defense, Quinn recalled an incident back in 1998 or 1999 when she was summoned by Jackson to a Beverly Hills hotel and requested her to give him propofol.

Jackson reportedly wanted to use the anesthesia to help him fight insomnia, and Quinn told him propofol would not help him get restful sleep. But, according to AP, Quinn testified that Jackson said he had the best sleep when he was under the effect of the medicine.

Jackson made the request when he was undergoing dental treatments, and Quinn told the court that she gave the singer anesthesia for procedures done after the meeting at the hotel. She added that he never asked for propofol after the meeting or requested that he be kept on the drug longer than medically required, AP reported.

Wednesday’s hearing also recorded the statements of Cherilyn Lee, a certified nurse, who collapsed on the witness stand after describing how she unsuccessfully tried to prevent Jackson from using propofol.

According to a CNN report, Lee started treating Jackson in 2009 -- a few days after he signed a contract with AEG for a world tour -- and he looked healthier after Lee attempted to treat the singer’s insomnia with intravenous drips of a vitamin cocktail.

But, Jackson couldn’t sleep more than five hours a night and wanted to try propofol, which German doctors had used to treat his insomnia during a 1997 tour.

"I remember telling him that it wasn't something he wanted to use at home," Lee said on Wednesday, according to CNN. "It wasn't a safe medication. It was definitely not a medication for insomnia." But, Jackson "kept telling me 'You don't understand, doctors are telling me it's safe just as long as I am being monitored,'" Lee testified.