LOS ANGELES — Phil Spector's defense opened its case Tuesday with the testimony of a pathologist who said "objective scientific evidence" indicates the shooting of an actress was suicide, not murder.

Dr. Vincent Di Maio, a retired Texas medical examiner hired by Spector to review the 2003 death of Lana Clarkson, told jurors at the pop music legend's trial that blood and gunshot residue on her hands as well as the location of the wound convinced him the shooting was self-inflicted. (VIDEO)

"There is no objective scientific evidence that anyone else held the gun. Everything else is speculative," Di Maio said.

The defense began calling witnesses Tuesday after the judge informed the jury that prosecutors were unable to proceed because their final witness was "presently unavailable." Unless the state Supreme Court intervenes, a former attorney for Spector, Sara Caplan, is to be jailed Thursday for refusing to testify about missing evidence in the case. If she continues to refuse, prosecutors will ask to read jurors a transcript of her testimony at a hearing before they rest their case.

Spector, 67, faces 15 years to life in prison if convicted of murder.

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Di Maio is the first of a string of defense experts expected to challenge the murder allegation on the basis of forensics. Di Maio directly contradicted the findings of the pathologist at the Los Angeles County Coroner's office who conducted Clarkson's autopsy. That deputy medical examiner testified earlier this month that her death was a homicide, but acknowledged that the medical evidence was inconclusive and he had based his ruling on other information provided by investigators. That information included Clarkson's state of mind and Spector's statement to a chauffeur, "I think I killed somebody."

Di Maio brushed off those considerations as "speculating about what people said, what people did, what people felt."

Dropping his voice to a whisper, Di Maio leaned toward jurors and said, "Anything could be anything, but when you stick to the objective scientific facts, it is a suicide." (VIDEO)

He told jurors that in his 38 years of experience as a pathologist "people do not want to accept suicides so they will try to make suicides into homicides."

He cited large amounts of gunshot residue on Clarkson's hands and contrasted it with the particle of confirmed residue recovered from Spector's hands.

"The person who has abundant particles is most consistent with having the gun, not the person with one particle," Di Maio said.

Prosecutors contend Spector washed his hands after the shooting, erasing most of the residue.

Di Maio also pointed to blood spatter on her hands, which he said was the suicide equivalent of a positive pregnancy test.

"It is not always present, but if it is there, it is there," he said.

Prosecutors have said Clarkson's hands are spotted with blood because they were likely on the gun trying to push or pull it out of her mouth when it discharged.

Di Maio also ticked off a list of statistics which supported suicide. He said 87 percent of women who kill themselves do so by shooting themselves and 76 percent of those fire into their heads.

He said that in his experience, 99 percent of intraoral gunshots, those discharged within the mouth, are suicide.

He is to continue testifying Wednesday.

Spector appeared pleased with his expert's turn on the stand. In the courtroom hallway, the defendant locked Di Maio in a warm embrace and patted him on the back.