Michael Jackson may have been 'dependent' on opioids, an addiction expert told jurors yesterday.

Dr. Robert Waldman took to the stand on Thursday in the ongoing trial against Dr. Conrad Murray. Murray has been accused of involuntary manslaughter after Jackson died in June 2009 from acute Propofol intoxication.

Dr. Waldman believed that Jackson 'was probably addicted to opioids,' specifically the drug Demerol in the months before he died. Demerol is a highly addictive painkilling drug that is used often for labour pain relief.

Dr. Waldman studied Jackson's medical records specifically focusing on the dosage of drugs that the singer received over the course of a few years.

The physician noticed 'six weeks of very frequent high-dose use' of the drug in 2009 when Jackson made visits to his dermatologist. Jackson's former dermatologist Dr. Arnold Klein regularly gave the singer wrinkle filling Botox and perspiration decreasing Restylane treatments. Dr. Klein also provided Jackson with Demerol.

The singer was injected with nearly 200mgs of the drug when he first began visiting Dr. Klein in March 2009. By May of the same year Jackson was receiving 300mg per visit.

Dr. Waldman believes that Jackson's intake of Demerol during this time period 'would result in opioid dependence in any of us.'

Jackson's 'insomnia' may have been a result of his withdrawal from the drug, Dr. Waldman asserted.

Murray's defence claims that he treated Jackson with Propofol to help the singer sleep.

The defence's final witness anaesthesiologist and Propofol expert Dr. Paul White took to the stand after the addiction expert concluded his testimony.

Dr. White conducted a study on Beagle dogs earlier in the trial where he orally administered doses of Propofol to animals to see whether it would be possible for someone to die from orally ingesting Propofol.

Dr. White confirmed today that it would be impossible for anyone to die from drinking the anaesthetic.

The defence is expected to rest its case today. If that happens, the judge has tentatively scheduled closing arguments for next week.

Dr. Murray could face up to four years in prison if convicted and faces the revocation of his medical licence.

The trial continues.