It was the collapse of a stage bridge in 1999 that injured Jackson's back, according to Dr. William Van Valin, who treated him for pain two years later.
In a video shown in court, Jackson kept singing as if nothing had happened, but that's not what Jackson told Van Valin.
In a video deposition, Van Valin testified that Jackson's injury was real. For a year, he made house calls to Neverland Ranch to give the singer injections of the painkiller Demerol in growing amounts. But doubts began to build.
Van Valin suspected Jackson was getting Demerol from someone else at the same time. Jackson appeared high.
"It was a bit scary. I sat there with him until it went away," said Van Valin.
One day, the doctor saw a band aid on Jackson, covering a needle mark.
"I said, 'Michael, you have another doctor that gave you a shot. You realize what risk you put yourself and me at by doing that? Who came and gave you a shot?'" said Van Valin.
According to Van Valin, Jackson's response was that he didn't get a shot from another doctor.
"But it was. He was lying," said Van Valin.
Another incident that disturbed Van Valin was when Jackson showed him a box of the anesthetic propofol, which he said he used to sleep while on tour. Propofol is the anesthetic that ultimately caused Jackson's death.
Katherine Jackson blames Jackson's tour promoter AEG Live for allegedly hiring Dr. Conrad Murray, who was attending the star when he died. AEG says Jackson's habit with meds began decades before. The defense team shows a pattern of Jackson befriending multiple doctors at the same time, giving each the same impression that Van Valin had.
"In my opinion, and I think in Michael's too, we were best friends. I didn't have a better friend, and I don't think he did," Van Valin said.
The defense says they may complete their case by the middle of next week. The plaintiffs are told to be ready with their rebuttal case.