(c) 2009, Los Angeles Times LOS ANGELES -- A sleepless Michael Jackson spent his last hours begging his doctor for a dose of a powerful anesthetic. For six hours, Dr. Conrad Murray resisted -- fearful that the pop star had developed a dangerous addiction to propofol, according to court records unsealed Monday. Instead, Murray administered the sedatives Valium, lorazepam and midazolam -- five times over six hours. But none put Jackson to sleep, and he continued to demand his 'milk,' the word the pop star used for propofol. Murray finally relented and at 10:40 a.m. added the drug to Jackson's IV, according the records. That dose -- mixed with the cocktail of other sedatives in the pop-star's system -- was enough to kill him, concluded the Los Angeles County Coroner's office in a preliminary toxicology report cited in a search-warrant affidavit unsealed Monday in Houston. These documents address one of the central questions in the Jackson death investigation: What killed him. The coroner's office, according to the records, said it found 'lethal levels' of propofol in Jackson's system. The records also lay out the first detailed chronology of Jackson's final hours June 25 -- and reveal Murray's fateful decision to give Jackson the drugs despite his suspicions that the pop star was becoming addicted to them. Authorities still have not disclosed how Jackson or Murray obtained the propofol, which is typically used in hospitals by anesthesiologists. Another unanswered question is exactly when Jackson stopped breathing. Both are important to the criminal investigation. Police said Murray told them he found Jackson not breathing at 11 a.m. -- a contention Murray's attorney disputes -- but paramedics were not called until nearly 90 minutes later. During that time, police suspect that Murray made three cell-phone calls that total 47 minutes, according to the affidavits, filed in June when authorities sought search warrants for Murray's Houston medical office and storage unit. And, Murray failed to tell paramedics or emergency room doctors that he had administered propofol, an omission that calls into question Murray's treatment and could bolster pursuit of an involuntary manslaughter charge, authorities said. 'Michael Jackson was not the usual patient with the usual problems in the usual circumstances,' said Murray's attorney, Edward Chernoff, in response to the court records. 'Dr. Murray's overriding goal was to try to help him. ... To place negligence on him simply because he was there, I don't think is fair.' Authorities have sought records from at least five physicians who treated Jackson as well as pharmacies in Las Vegas and Beverly Hills, but Murray is the only one named in court documents as the target of the manslaughter investigation. Jackson specifically had asked AEG Live to hire Murray as his $150,000-a-month physician to travel with him to London, where he was scheduled for a 50-concert comeback tour. Two days after Jackson's death, Murray agreed to a three-hour police interview in which he described his patient as having insomnia and a worrisome addiction to propofol, records show. At Jackson's request, Murray had been administering 50 milligrams of the drug in the six weeks before his death using an intravenous line, according to court records. But after weeks of use, Murray said he tried to wean the pop star off the medication. Murray told detectives that he lowered Jackson's dosage to 25 milligrams and mixed it with two other sedatives, lorazepam and midazolam. Then, on June 23, he administered those two medications and withheld the propofol -- and Jackson was able to sleep. On June 25, Murray once again tried to induce sleep without resorting to propofol, according to the affidavit. He first gave Jackson the three alternative sedatives at 1:30 a.m., 2 a.m., 3 a.m., 5 a.m. and 7:30 a.m. But Jackson remained awake. Finally, 'after repeated demands/requests from Jackson,' Murray relented and gave Jackson 25 milligrams of propofol, diluted with another sedative, records state. Medical experts said that a 25 milligram-dose for someone Jackson's size should not have been enough to kill him. But combined with other drugs, the propofol could have been more dangerous. 'You start giving a lot of drugs and don't know what the final effects might be,' said Dr. Scott Engwall, vice chair of the Department of Anesthesiology at the University of California, Irvine School of Medicine. 'When you give a little bit of this and a little bit of that, it starts adding up.' According to the court records, Murray sat at Jackson's bedside for 10 minutes after he fell asleep, before leaving to use the restroom for no more than two minutes. When he returned, he found Jackson not breathing and said he immediately began administering CPR as well as a drug to reverse the effects of the sedative. Murray's attorney criticized the timeline outlined in the document as 'theory, not fact' and disputed the significance of the phone calls. 'Dr. Murray never said 10 minutes. He said he watched him long enough that he felt comfortable,' Chernoff said. 'Their theory is he ... goes off to make some social calls and comes back and finds Michael Jackson is dead and is negligent. The implication is that he left the room to make the phone calls. He didn't need to leave the room to make the calls.' Chernoff declined to say why Murray did not immediately tell paramedics and emergency room doctors that he had given Jackson propofol. Los Angeles Police Deputy Chief Charlie Beck said the investigation was ongoing and that the findings would be forwarded to county prosecutors who ultimately will determine whether to file criminal charges. 