David Cragun, a cardiologist, testified that 50-year-old Michele MacNeill had mild myocarditis, a condition that is usually not enough to kill a person.
"The chance of a serious or life-threatening complication would be very rare," Cragun testified. "… I think the lack of symptomatology and [previous] lab work make it very unlikely that [Michele MacNeill's] myocarditis was severe enough to provide a significant risk of cardiac death."
Another expert, Florida-based forensic pathologist Joshua Perper, testified Friday that he did not find any evidence of myocarditis in the slides containing small slices of Michele MacNeill's heart that he analyzed.
"My opinion was that Michele died of drowning," Perper said. "In addition, that she had some drugs on board, in my opinion, that could have contributed to her death."
Perper said several factors led him to the conclusion of drowning, including that her lungs were heavier than normal, and her blood was diluted indicating that her bloodstream absorbed water that she had inhaled. This led him to believe that the drug levels found in her body after her death may also have been diluted, he testified.
But Perper said that he also classified Michele MacNeill's manner of death as "undetermined," saying there was not enough evidence to conclude without a doubt that a homicide occurred.
"There were a lot of suspicious elements in my evaluation," Perper testified.
However, Perper admitted under cross-examination that it is possible Michele MacNeill died of drowning combined with a heart arrhythmia but said arrhythmia is difficult to determine after death.
The central question of the 4th District Court jury trial is whether Michele MacNeill was murdered at the hands of her husband or died from natural causes.
Martin MacNeill, 57, is on trial for murder and obstruction of justice, accused of killing his wife in order to continue an affair with 37-year-old Gypsy Willis. Friday ended the third week of what is expected to be a five-week trial.
Martin MacNeill allegedly gave his wife a toxic combination of prescription medications after she came home to recover from plastic surgery in April 2007. Prosecutors claim Martin MacNeill drowned her in a bathtub in their Pleasant Grove home after the mixture of drugs rendered her unconsciousness. Four drugs were found in Michele MacNeill's body at the time of her death: oxycodone, promethazine, diazepam and zolpidem, which is also known as Ambien.
Utah assistant medical examiner Maureen Frikke who died in 2008 performed an autopsy shortly after Michele MacNeill's death and determined her demise was natural, the result of cardiovascular disease matched with high blood pressure and an inflamed heart.
But investigators claim Martin MacNeill called Frikke multiple times and gave misleading information about how her body was found in their bathtub on April 11, 2007.
In 2010, in a new investigative report, Chief Utah Medical Examiner Todd Grey changed the cause of Michele MacNeill's death to the combined effects of heart disease and drug toxicity. The manner of death was changed to "undetermined."
During testimony on Thursday, Grey said he did see some evidence that Michele MacNeill may have drowned and pointed to reports from medical responders who said that while undergoing CPR, the woman coughed up several cups of water, some of it pink and frothy. But Grey said he could not be sure if that water came from her lungs or stomach.
Though Grey said he did not see enough evidence in her lungs to indicate to him that she died of drowning, he said it could still be possible.
Ada MacNeill, then 6, found her mother fully clothed and face-up in the bathtub, according to the girl's interview with the Children's Justice Center in 2008. The child went to a neighbor's house to get help, and eventually Michele MacNeill was pulled from the bathtub by a neighbor and Martin MacNeill. The two attempted CPR before medical crews arrived.
Those medical crews also attempted to perform CPR and other life-saving efforts before Michele MacNeill was taken to an American Fork hospital, where she was pronounced dead.
Testimony will continue Tuesday, when several prison inmates are expected to testify that Martin MacNeill confessed to them that he killed his wife. Those inmates were housed in federal prison with Martin MacNeill when he was serving time for a previous ID fraud conviction.