SALT LAKE CITY (AP) -- A medical examiner testified Thursday he was unable to prove how the wife of a Utah doctor charged with murder died, complicating an eventual decision by jurors in the case.
The witness, Todd Grey, said Michele MacNeill's heart may have stopped beating because of a combination of heart disease and drug toxicity, and that it was possible the 50-year-old woman drowned in a bathtub where she was found.
"I didn't believe I had enough to justify homicide," Grey testified about his finding in the case involving defendant Martin MacNeill.
Grey said an irregular heartbeat was the most probable manner of death, but he doesn't know what caused it. A heart arrhythmia "leaves no footprints" that can be detected by a forensic pathologist, he said.
Grey's testimony came a day after a mistress of Martin MacNeill, 57, testified that the doctor once described how he could induce a heart attack in someone that would appear natural.
Anna Walthall said MacNeill told her over "pillow talk" in 2005 that "'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.'"
One of Grey's subordinates initially ruled that Michele MacNeill's 2007 death was natural from heart disease, and that she had high blood pressure and was developing myocardosis, or inflamed heart tissue that could have interfered with a normal heart rate or rhythm, he said.
Investigative findings prompted Grey to change the autopsy finding to undetermined -- and to add that drug toxicity may have played a role.
Those investigative findings "raised a question as to whether this was a simple, straightforward, natural death," said Grey. He wasn't asked to elaborate on the stand.
However, the change to undetermined opened the way for the murder charge against Martin MacNeill.
Prosecutors have said he hounded Michele MacNeill to get cosmetic surgery, then knocked her out with painkillers, Valium and sleeping pills and left her to die in a bathtub.
For the first time in the trial, prosecutor Chad Grunander suggested that MacNeill "held her down to cause her death."
Defense lawyers argue she had a heart attack and fell into the tub.
Grey said he couldn't confirm that she drowned, but it is possible. He said her lungs were about twice their normal weight, possibly because they were saturated with fluid or blood congestion, "but I couldn't use those findings alone to prove drowning."
Emergency medics previously testified Michelle MacNeill expelled two or three cups of fluid from her mouth when they performed chest compressions. But Grey said it wasn't clear if the water came from her lungs or stomach.
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