The doctor who performed Michael Jackson's autopsy on Tuesday testified that he determined Jackson's death was a homicide.

Dr. Christopher Rogers, the Los Angeles County chief of forensic medicine, told jurors in the manslaughter trial of Dr. Conrad Murray that a lack of precise dosing equipment in Jackson's bedroom caused Dr. Conrad Murray incorrectly estimating how much propofol he had given to the singer.

Rogers acknowledged the amount of propofol present in Jackson's blood was too high to have been caused by the relatively small infusion of 25 milligrams that Murray told police he gave the pop star.

Prosecutors have argued that Murray likely followed up his infusion of propofol with a continuous drip of the drug supplied through an IV system.

However, his attorneys have claimed that Jackson caused his own death by giving himself an extra dose when Murray was out of the singer's bedroom.

Rogers admitted that Jackson, while laying in bed, could have reached an injection site just below the knee, where drugs were administered to him through an IV line.

But, Rogers said he did not believe Jackson would have had time to give himself the anesthetic and stop breathing in the two minutes that Murray told police he was out of the room.

Witnesses and phone records have shown that Murray was on the phone or writing e-mail for more than 45 minutes before prosecutors believe he found Jackson's lifeless body, and an ambulance was called.

"The problem that Mr. Jackson was having was that he couldn't sleep, and it's not appropriate to administer propofol in that situation. The risk outweighs the benefit," Rogers said.

Murray could face up to four years in prison if convicted.