One of the most anticipated witnesses expected to take the stand during the trial was Ava, who was two at the time of her mother's death and seven at the time of the trial. However, she would never take the stand. Instead, jurors heard testimony from state police detective Kimberly Squire, who interviewed Ava shortly after she was found unharmed and clinging to her mother's body. According to Squire, Ava likely never witnessed the murder. If she had, there was a significant chance that her memory of the event would be deemed unreliable evidence based on her age and the amount of time that passed between the murder and the trial.
Into the second week of the trial, jurors heard more gruesome testimony from pathologist Dr. Henry Nields, who testified about Christa's autopsy. He claimed that by the time the medical examiner began his investigation, she has probably been dead for a day or a day and a half, and was unable to give a precise time of death. Nields told jurors that Christa had defensive wounds on her hands and that she also had cuts and bruises on her torso and face, as well as blunt force trauma to her head. The fatal blow was from a stab wound from a knife to her left lung that was delivered with such force that the one-inch-wide blade that pierced her actually nicked the floor below her, Ryan reported. Nields testified that because there was no evidence of trauma to Worthington's genitalia, it was not certain whether a sexual assault took place, even though McCowen's sperm was found at the scene.
Even though McCowen's DNA had been discovered on and near Christa, interestingly enough, his fingerprints were not, state police Lt. Monte Gilardi testified. "Of the nine finger and palm prints lifted from inside Worthington's cluttered Truro home, from various items secured from the house, and from her car parked outside, none were McCowen's," Hilary Russ of the Cape Cod Times reported. Moreover, none of the prints were found to belong to the emergency responders who came to the house. Later testimony by DNA examiner Christine Lemire revealed that Christa also had the DNA of at least three unidentified men under the fingernails of her right hand, genetic profiles that also did not match McCowen's. The big question that many wondered about was whether some of the DNA belonged to Frazier, the man who McCowen blamed for the murder, or someone else.