Dr. Allan Metzger, Michael Jackson's former physician, takes the witness stand during Dr. Conrad Murray's involuntary manslaughter trial in Los Angeles Superior Court on Oct. 24, 2011 in Los Angeles

*Prosecutors rested their case against Michael Jackson’s doctor on Monday after nearly four weeks of testimony intended to prove he was responsible for the pop star’s death.

The last of 33 prosecution witnesses in the involuntary manslaughter trial of Dr. Conrad Murray was anesthesiology expert Dr. Steven Shafer, who wrapped five days on the witness stand by telling jurors Murray should not have given Jackson the anesthetic propofol as a sleep aid.

“There’s very little, almost no precedent for this level of propofol exposure,” Shafer said. Medical examiners found that Jackson died from an overdose of propofol combined with sedatives.

Shafer said it was in some ways difficult to analyze the singer’s death because it was so unusual.

After prosecutors rested, Murray’s attorneys called their first defense witness – Jackson’s longtime physician, Dr. Allen Metzger, who told the court he visited the singer on April 18, 2009, and that Jackson asked him about “intravenous sleep medicine” — a possible reference to propofol, which is given intravenously.

Metzger said he was unsure what type of medication Jackson was seeking, but he did not give it to him.

Cheryln Lee, a nurse who treated Michael Jackson for sleep disorder in early 2009, testifies during Dr. Conrad Murray's involuntary manslaughter trial in Los Angeles Superior Court on Oct. 24, 2011 in Los Angeles

Also on Monday, Metzger and nutritionist Cherilyn Lee, a nurse who treated Jackson in 2009, testified the singer had complained to them of his severe insomnia.

Defense attorneys have sought to portray Jackson as highly familiar with the powerful propofol, motivated to obtain it and able to use it on himself.

Murray told police he had struggled to control Jackson’s insomnia and tried to ween him off propofol in his final days.

Murray has admitted giving Jackson propofol, the key drug that caused the “Thriller” singer’s overdose, but defense attorneys have argued that Jackson gave himself an extra, fatal dose of the drug when Murray was absent.

Prosecutors have put Murray’s defense attorneys in a quandary by presenting the doctor’s account to police of what happened in Jackson’s final hours, then pointing out glaring inconsistencies between his statements and the evidence.