One of the most contentious issues in the upcoming Dr. Martin MacNeill murder trial may be exactly how his wife died on April 11, 2007.
Prosecutors say Martin MacNeill, who is also an attorney, used his medical knowledge to kill Michele MacNeill as she recuperated from a face-lift by drugging her and then drowning her. Michele MacNeill was found dead in a bathtub in the family's Pleasant Grove, Utah, home 10 days after the surgery. Medical examiners found a powerful cocktail of drugs -- including Valium, Percocet, Phenergan, and Ambien -- in her system.
Martin MacNeill has pleaded not guilty to the charges of first-degree murder and obstruction of justice, and his attorneys have told reporters that their client is looking forward to the chance to prove his innocence.
The medical examiner, Dr. Maureen Frikke, who conducted Michele's autopsy said she died from cardiovascular disease.
"This 50-year-old Caucasian female appears to have died as the consequence of natural cardiovascular disease. Postmortem examination revealed anatomic evidence of chronic hypertension and myparditis, which are capable of causing acute unexpected arrhythmias and sudden death," wrote Frikke in her report concluding Michele MacNeill died of natural causes.
The case was closed for about a year and half until it was reopened on the insistence of some of Michele MacNeill's family members. Eventually, another medical examiner, Dr. Todd Grey, reviewed the case and determined Michele MacNeill died from "combined effects of heart disease and drug toxicity," but could not determine if Michele MacNeill's death was a homicide or natural.
Then, yet another doctor reviewed the case, Dr. Joshua Perper, who says Michele MacNeill died as a result of drowning, but he also couldn't determine whether she died as a result of an accident or whether it was a homicide.
HLN asked forensic pathologist Dr. Dan Spitzto review the case to explain what he thinks happened to Michele MacNeill. Spitz has practiced pathology for 12 years, conducting more than 5,000 autopsies. He is the chief medical examiner for Macomb County, Michigan.
Although it's unclear whether Michele MacNeill administered the drugs herself or not, Spitz said the drugs circulating in her body could have easily killed her by working in concert to depress her central nervous system.
"These drugs can act in a synergistic fashion, which means they work together to affect an individual. The way it can affect you is that it can cause you to be lethargic. It can cause confusion. It can cause an individual to become drowsy up to the point of causing an individual to be very sleepy to become unresponsive, difficult to arouse, and ultimately as brain function is depressed, as breathing is depressed you start to have difficulty breathing, and ultimately your respiratory drive or desire to continue to breath normally is affected and your breathing will stop," said Spitz.
Michele MacNeill likely ingested the drugs within hours of her death. Spitz says she could have started to feel the effects of the medications within minutes of ingesting them.
"That process from time to ingestion to comatose could be as early as 20 to the 30 minutes up to a couple of hours. Then the period of being comatose could last for a very short period of time or it could go on for a period of hours, and at some point the person stops breathing and death occurs," said Spitz.
In a bizarre twist, prosecutors are expected to call Anna Osborne Walthall, who claims to be Martin MacNeill's former lover, to testify about how he bragged to her that he could induce a heart attack in someone by injecting them with potassium, and how a medical examiner would not be able to detect it.
"If you inject someone with potassium, you can alter their electrolytes and potentially put someone in cardiac arrest," said Spitz. "That's not easy to do, because you have to inject someone against their will. It would be very hard to detect as far as the potassium goes, because potassium is normally present in the body and you really can't test it after death with any degree of certainty as to the level, and that's because the levels of potassium change in the body change rapidly after death."
Spitz added: "Even insulin needles are very small and can be used to inject somebody. If you found somebody in a compromised state, there are a lot of things you could do to them that could go undetected."
Spitz said it may be difficult for prosecutors to prove their case against Martin MacNeill beyond a reasonable doubt, because there isn't a consensus on what killed his wife.
"There's lots of pieces to this process as far as sorting out cause and manner of death, and when that's the case and you have competing causes of death, and things aren't that certain, it creates a problem for the prosecution," said Spitz. "There's just a lot of things from what I am gathering that need to be proven. You need to prove the medications were given against somebody's will. You need to show they were given by somebody else and that she was put in the bathtub by somebody else. That she didn't die of an accidental overdose where she took the medications on her own then got into the bathtub. That she didn't die from her underlining cardiac disease."
Jury selection in Martin MacNeill's trial is scheduled to begin Tuesday. If convicted of murder, Martin MacNeill could spend the rest of his life behind bars.