Michael Jackson's oldest son, Prince, could be called as a rebuttal witness by the prosecution in the involuntary manslaughter trial of Dr. Conrad Murray, a source close to the Jackson family reveals exclusively to RadarOnline.com.

Even though the prosecution hasn't rested its case, there is a very real possibility that Prince will be called as a rebuttal witness by Deputy District Attorney David Walgren.

"Prince is willing, able, and very much wants to testify. The district attorney's office is in contact with Katherine Jackson about Prince testifying,” a Jackson family insider tells us. “The district attorney's position is right now -- that Prince not be called in their case. It will be a strategic decision to put Prince on the stand."

Dr. Conrad Murray's defense team has told jurors that the personal physician to Michael Jackson gave him 25 milligrams of Propofol, but RadarOnline.com has exclusively learned that the King of Pop had significantly higher levels of the powerful anesthetic in his system at the time of his death.

Dr. Murray's lawyers contend that when the Houston-based cardiologist left the superstar singer briefly on the morning of June 25, 2009, he grabbed a bottle of the drug, ingested it, and then subsequently died.

As testimony in the involuntary manslaughter trial enters its second week, it's expected that Deputy District Attorney Dave Walgren will be calling medical witnesses, including the coroner, who will reveal that: "Michael had toxic and lethal levels of Propofol in his system at the time he died. The levels of Propofol were extremely high, much higher than 25 milligrams of Propofol that Dr. Murray says he gave to Michael Jackson," a source close to the situation tells RadarOnline.com.

Dr. Conrad Murray’s attorney appeared in a Los Angeles courtroom Wednesday afternoon to appeal to the LA County Coroner to perform tests on forensic evidence in the criminal case surrounding Michael Jackson’s death – but refused to recognize the coroner’s declaration at the judge’s request, RadarOnline.com has learned.

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District Attorney Dave Walgren countered, asking the defense to acknowledge that the Coroner might destroy the evidence in question during the testing.

"I'm not going to litigate the facts. The defense seems to be operating under the guise that Michael Jackson killed himself,” Walgren said Wednesday during the court hearing.

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“They won't come out and say that, but that is where they are headed."

Walgren didn’t object to testing, he just asked that it be done correctly and that a chain of custody be placed for the evidence.

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Judge Pastor told Murray’s attorney, Michael Flanagan, any order he would sign off on must include that the defense acknowledges certain elements of the coroner's declaration.

Flanagan was not ready to make that concession yet.

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As RadarOnline.com previously reported, Murray’s attorneys say the fluid testing is urgent before the evidence deteriorates. Prosecutors are asking the doctor’s attorneys be given only half the residue in the syringes and will only agree to the testing if it’s done correctly.

Murray plead not guilty to involuntary manslaughter for allegedly injecting Jackson with drugs the night he died.

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Despite media reports that there would be 20 witnesses called for the preliminary hearing, the DA said it would be approximately 35 witnesses.

Murray did not appear in court Wednesday for the hearing.

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