Dr. Christopher Rogers, who conducted the autopsy on Jackson, refuted the key claim by defense lawyers for Dr. Conrad Murray that Jackson self-administered the drug when Murray briefly left the room.
Rogers told jurors a more likely scenario was that Murray misjudged how much propofol he gave the entertainer.
He said he considered a number of factors in ruling the death a homicide. Among them were Murray's statements to police and the lack of sophisticated medical equipment in Jackson's bedroom, where the superstar had been receiving the anesthetic as a sleep aid.
"I think it would be easy under the circumstances for the doctor to estimate wrong and give too much propofol," Rogers said.
Murray has pleaded not guilty to involuntary manslaughter. Prosecutors were expected to call a leading expert on propofol as a witness later in the day.
Rogers' testimony came after jurors heard the end of Murray's June 27, 2009, recorded interview with police in which he first disclosed he had been giving Jackson propofol to help him sleep.
Prosecutors played the remaining 40 minutes of the interview, which included Murray's description of informing Jackson's mother and children that the entertainer had died.
"After they cried and cried and cried, then his daughter uttered a lot of words of unhappiness," Murray told detectives, saying Paris Jackson was afraid of being alone after her father's death.
"`I know you tried your best, but I'm really sad,"' he continued, recounting her words. "`I will wake up in the morning, and I won't be able to see my daddy."'
Jackson's mother, Katherine, dabbed her eyes with a tissue as the recording played.
A police detective who helped conduct the interview told jurors that Murray seemed surprised when, toward the end of the interview, he learned that three bags of medical items had not yet been recovered from the star's bedroom.
The recording ended shortly after the physician explained the items could be found in a closet.
The interview helped transform the investigation into Jackson's June 25, 2009, death from a simple death inquiry into a homicide case.
Murray told the detectives he always put the medications and equipment he used on Jackson away "because he wanted me not to have anything hanging around."
Detective Scott Smith then asked, "Where's your bag where those syringes would be now?"
"Oh, really?" replied defense lawyer Ed Chernoff.
"I don't have them," Murray replied, before telling the detectives where to find the bags.
Smith testified that Murray had a startled expression when he learned detectives hadn't yet recovered the bags.
"He seemed very surprised," Smith said.
Smith said he and his partner sat down with Murray and his attorney without knowing much about Jackson's death.
"At this time, we didn't have any answers," Smith said. "It definitely wasn't an interrogation."
Smith attended Jackson's autopsy, which revealed no obvious signs of trauma or immediate cause of death. In fact, Rogers told jurors the singer appeared to be in better shape than most other 50-year-old men.