Michael Peterson | The Murder of Kathleen Peterson | Crime Documentaries

On December 9, 2001, Peterson called an emergency line to report that he had just found Kathleen unconscious and suspected she had fallen down "15, 20, I don't know" stairs. He later claimed that he had been outside by the pool and had come in at 2:40am to find Kathleen at the foot of the stairs. He maintained she must have fallen down the stairs after consuming alcohol and valium. Toxicology results showed that his wife's blood alcohol content was 0.07 percent. The autopsy report concluded that the 48-year-old victim sustained a matrix of severe injuries, including a fracture of the thyroid neck cartilage and seven lacerations to the top and back of her head, consistent with blows from a blunt object, and had died from blood loss 90 minutes to two hours after sustaining the injuries. Kathleen's daughter, Caitlin, and her sister, Candace Zamperini, both initially maintained Michael's innocence and publicly supported him alongside his children, but Zamperini reconsidered after learning of Peterson's bisexuality, as did Caitlin after reading her mother's autopsy report, and both subsequently broke off from the rest of the family. Although forensic expert Dr. Henry Lee, hired by the defense, testified that the blood-spatter evidence was consistent with an accidental fall down the stairs, police investigators concluded that the injuries were inconsistent with such an accident. As Michael Peterson was the only person at the residence at the time of Kathleen's death, he was the prime suspect and was soon charged with her murder. He pleaded not guilty.

The medical examiner concluded that Kathleen had died from lacerations of the scalp caused by homicidal assault. According to this medical examiner, the total of seven lacerations to the top and back of her head were the result of repeated blows with a light yet rigid weapon, a blow pole which was a gift by Kathleen's sister, but wasn't recovered at the scene of the crime...that is, not at that time. Regardless,The defense disputed this theory, claiming that Kathleen's skull had not been fractured by the blows and nor was she brain damaged, which was inconsistent with injuries sustained in a beating death, according to their analysis.