If Jackson's death was caused by his doctor, then whoever hired the doctor for the star's comeback tour should be liable for his death, according to Katherine Jackson's lawsuit.
Now under scrutiny before the jury is Murray's independent contractor agreement, which was drawn up by AEG Live but never signed. The AEG defense says the document holds evidence that Jackson requested Murray to be his personal physician and dictated his salary.
Attorney Kathy Jorrie, who wrote the agreement, walked the jury through the many changes made to the document. Her appearance set off objections from the Jackson attorneys.
"She never spoke to Michael Jackson, she doesn't know. But we know that, at least based on the evidence, AEG did hire Dr. Murray. And the contract she negotiated was never sent to any representatives of Michael Jackson," said Jackson attorney Brian Panish.
The defense says Jorrie spoke directly to Murray about the terms the doctor and Jackson wanted.
"Michael Jackson wanted to bring his long-time physician with him. That it was at his solo and absolute direction, that this would only occur with his, um, normally saying he wanted it done, but he actually had to sign and say so, and had to sign and say that he would be the one paying for it," said AEG lawyer Marvin Putnam.
Jorrie says that she questioned Murray's salary of $150,000 a month. Murray's response, she testified, was that his practices in four states brought him $1 million a month.
Jorrie says she did an Internet search and found Murray's practices listed. She said the medical boards in the four states showed no record of disciplinary action against him.
Jurors learned through earlier testimony that Murray was broke. About Murray's contract not being signed, the Jackson attorneys say it doesn't matter.
"You don't really need a contract to hire someone. As we've seen in this case, many people have worked for AEG that didn't have a contract," said Panish.
But AEG's interpretation of the law is that the unsigned agreement nullifies everything.
"As long as you have that agreement that you're not going to have an agreement unless signed by the parties, then you can't override that," said Putnam.
Jorrie is back on the stand Wednesday to face cross examination by the Jackson attorneys.