On December 9, 2001, Peterson called an emergency line to report that he had just found Kathleen unconscious in their Forest Hills mansion 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 2:40 am to find Kathleen at the foot of the stairs. He said 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 (70 mg/100mL). The autopsy report concluded that the 48-year-old woman 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 Kathleen's sister, Candace Zamperini, both initially proclaimed 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. 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, Dr. Deborah Radisch, concluded that Kathleen had died from lacerations of the scalp caused by a homicidal assault. According to Dr. Radisch, the total of seven lacerations to the top and back of Kathleen's head were the result of repeated blows with a light, yet rigid, weapon. The defense disputed this theory. According to their analysis, Kathleen's skull had not been fractured by the blows, nor was she brain damaged, which was inconsistent with injuries sustained in a beating death.
The trial drew increasing media attention as details of Michael's private life emerged. Durham County District Attorney James Hardin, Jr. and the prosecutors (among them former District Attorney Mike Nifong) attacked Peterson's credibility, focusing on his alleged misreporting of his military service and what they described as a "gay life" he led and kept secret. The prosecution contended that the Petersons' marriage was far from happy, suggesting that Kathleen had discovered Michael's alleged secret "gay life" and wanted to end their marriage. It was the main motive that the prosecution offered at trial for Kathleen's alleged murder (the other being a $1.5 million life insurance policy). According to Assistant District Attorney Freda Black, Kathleen
would have been infuriated by learning that her husband, who she truly loved, was bi-sexual and having an extramarital relationship—not with another woman—but a man, which would have been humiliating and embarrassing to her. We believe that once she learned this information that an argument ensued and a homicide occurred.
The defense argued that Kathleen accepted Michael's bisexuality and that the marriage was very happy, a position supported by Michael and Kathleen's children and other friends and associates.
The prosecution said that the murder was most likely committed with a custom-made fireplace poker called a blow poke. It had been a gift to the Petersons from Kathleen's sister but was missing from the house at the time of the murder investigation. Late in the trial the defense team produced the missing blow poke, which they said had been overlooked in the garage by police investigators. Forensic tests revealed that it had been untouched and unmoved for too long to have been used in the murder. A juror contacted after the trial noted that the jury dismissed the idea of the blow poke as the murder weapon. https://en.wikipedia.org/wiki/Michae...rson_(criminal