Defense will focus on anti-anxiety drug Lorazepam in Jackson's death.
In a surprising move Wednesday Dr. Conrad Murray's defense lawyers abandoned a key part of their theory before the jury entered court.
They told Judge Michael Pastor that they will no longer try and prove that Michael Jackson may have orally ingested the powerful sedative Propofol.
Thursday's testimony focused on Jackson's struggle with insomnia.
Testimony continued with a sleep expert who said it was inconceivable Dr. Murray would use Propofol to treat insomnia.
During cross examination defense attorneys pointed out that 25 mg of Propofol, the amount Dr. Murray says he gave Jackson, is considered a very low dose.
Still, Dr. Nader Kamangar said each patient reacts differently depending on other factors such as underlying health issues or additional medications they might have taken.
"All bets are off then you really still can't be 100 percent sure that that is not enough to kind of tip them along that sedation continuing to cause a deeper level of sedation and compromise their ability to breath," he said.
Sources tell NBC News that Murray's defense is expected to claim Jackson took eight pills of the anti-anxiety drug Lorazepam hours before his death, but never told Dr. Murray.
The defense will argue that is what actually killed Jackson.
The defense will begin laying out its case next week.