"Michael was acting crazy in his last few hours, demanding drugs to help him sleep. He was always playing with the bottles, who knows what he did."
Murray will also claim Michael was able to inject himself to feed his addictions and had detailed knowledge of painkilling medications and intravenous treatments after decades of drug abuse.
The source added: "Dr. Murray is confident he can convince a jury Michael could have self-administered his drugs.
"It paints a bad picture of him as his doctor for feeding his addiction but Dr. Murray still insists he didn't dish out enough to kill him."
Meanwhile, a key witness in the case has gone missing.
Pharmacist Tim Lopez - who claimed he sent large amounts of a powerful anaesthetic to Murray's girlfriend shortly before the singer's death - has moved to Thailand without telling authorities, and his friends and family have reportedly refused to reveal his exact whereabouts.
Now, prosecutors want to use an earlier testimony he gave as part of their evidence, with Judge Michael Pastor expected to make a decision in the next few days.
Opening arguments in the trial are scheduled to begin on September 26.
If convicted, the medic faces up to four years in jail.
- BANG! Showbiz