A doctor who once treated Michael Jackson testified Monday during the involuntary manslaughter trial of Dr. Conrad Murray that he warned the pop star against using any IV sleep medication because of its dangers.

Dr. Allan Metzger, who was also friend of Jackson, testified that on April 18, 2009, that two months before Jackson's death, the pop star asked him about getting intravenous sleep medication, saying drugs taken orally didn't work.

Under cross-examination by a prosecutor, Metzger was asked: "Any amount of money that would have convinced you to give him propofol in his house?"

"Absolutely not," replied Dr. Metzger.

"When Michael Jackson inquired about intravenous sleep medication, you explained to him that was dangerous, life-threatening and should not be done outside of a hospital, is that correct?"

"That's correct," Dr. Metzger said.

Metzger said Jackson didn't name a specific drug but wanted "some form of an anesthetic."

"I don't recall him naming medicines... but I do remember him saying many medicines did not work... I had personally tried him on Tylenol PM, which did not work," said Dr. Metzger. "We had tried Zanax... and on that visit, I gave him Klonopin or trazodone, to be used not together."

Metzger testified during the first day of the defense case which is expected to end Thursday. The aim of Murray's attorneys was to show how desperate Michael Jackson was for drugs to help him cope with insomnia.

Murray’s lawyers are arguing against prosecutors' contention that Murray's reckless use of the surgical anesthesia propofol to help Jackson sleep makes him criminally responsible for the pop icon's death.

Defense lawyers claim that Jackson's desperation to sleep caused him to inject himself with the surgical anesthetic propofol, while Murray was in the bathroom, ending his own life.