Although the shamed doctor has been called to take the stand at Michael's mother Katherine's civil case against AEG Live - which accuses the company of being responsible for negligently hiring  Conrad to care for Michael – he will not answer questions because the responses could affect his appeal, according to TMZ.

The medic has already served a year and a half in prison after being found guilty of involuntary manslaughter following Michael's death, but his lawyer Valerie Wass is set to file documents arguing she is appealing his conviction and whatever he says in Katherine's lawsuit could be used against him.

Michael's son, Prince Michael, is expected to give evidence on conversations he had with his father about the concert promoter.

A source previously said: "Prince absolutely plans on testifying.

"Prince very much wants to take the stand and plans to tell jurors about specific conversations he had with his father about AEG. Prince will also testify about the fateful day his father died, as he was an eyewitness to the efforts that were made to save his life."

The 16-year-old's siblings, Paris, 15, and Blanket, 11, aren't expected to testify, however.

In the lawsuit, Katherine, 82, contends that AEG Live - which was behind the late singer's 'This Is It' comeback concerts at The O2 arena in London - were responsible for Dr. Murray and failed to properly vet the physician before hiring him.

The 'Thriller' hitmaker died in June 2009 after being administered a lethal dose of Propofol by Murray.
The trial is set to begin on April 2.