(PROVO, Utah) -- Utah's chief medical examiner testified Thursday that though a cause of death for Michele MacNeill was never determined, the prosecution's theory that she was drowned was plausible.
When asked by prosecutors if it was possible MacNeill died after being drugged and held down in a bathtub full of water, Utah State Chief Medical Examiner Dr. Todd Grey said it was a possibility.
MacNeill's cause of death was changed by Grey from "natural" to "undeterminable," he said, due to the possibility that drugs could have played a role in her death.
Despite the change, Grey told the court, "I did not feel I could reach a conclusion of homicide."
Dr. Martin MacNeill, 57, is on trial for the April 11, 2007, death of his wife, Michele MacNeill, 50. Prosecutors allege MacNeill persuaded his wife to have plastic surgery so he could dope her up during her recovery and then drown her -- all so he could pursue a relationship with a mistress, Gypsy Willis.
MacNeill's defense lawyers said heart problems were a contributing factor in the death of the mother of eight.
Dr. Maureen Frikke, a former assistant medical examiner who died in 2008, certified that MacNeill died of cardiovascular disease, high blood pressure and inflammation of the heart. That report was amended after Grey reviewed the case after Frikke's death.
On Wednesday, Anna Osborne Walthall, one of two women who have testified that they had a sexual relationship with Dr. MacNeill while his wife was still alive, said the doctor once explained to her during "pillow talk" how he could induce a heart attack in someone while making it appear natural.
"There's something you can give someone that's natural that's a heart attack that's not detectable after they have a heart attack," she quoted MacNeill as saying.
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