Prosecutors argued that at least one hair fragment found in pliers recovered on Peterson's boat belonged to Laci. The defense disagreed and disputed the validity of the tests on the hair fragments. There was no blood evidence.
Because of the lack of physical evidence, prosecutors had to rely on a largely circumstantial case that was built on Peterson's multiple lies and details of his arrest. From Frey's testimony and her wiretapped phone conversations with Peterson, jurors learned the fertilizer salesman told her he wanted them to be together and told elaborate lies to keep his marriage secret.
Before Laci's disappearance, Peterson told Frey he was a widower and preparing to celebrate his first Christmas without his wife. During one phone conversation -- which took place as investigators and volunteers were searching for Laci -- Peterson told Frey he was in Paris on a business trip.
Peterson, prosecutors also argued, looked like someone trying to elude authorities when he was arrested on April 18, 2003. Normally clean-shaven and dark-haired, Peterson had grown a mustache and goatee and bleached his hair. In addition, he had purchased a car using his mother's name, had $15,000 cash, a large backpack, and an overnight bag stuffed with hunting knives, a water purifier, snorkeling and fishing equipment, a shovel, and duct tape. Peterson also had several changes of clothes, four cell phones, two driver's licenses and six credit cards.
Peterson did not testify during his trial. Geragos questioned the lead investigator in the case about Peterson's multiple affairs, suggesting that he would not have committed murder to continue his relationship with Frey.
Geragos tried to explain Peterson's behavior through the testimony of his parents. Jackie Peterson testified that she had mistakenly withdrawn $10,000 from her son's account and gave it back to him the day before his arrest. That, she said, explained the large amount of money he was carrying. She also said she told her son to buy the car in her name because police periodically impounded his vehicles to search for evidence.
Lee Peterson testified that he told Scott Peterson to get his brother's license the day before the arrest so he could get a San Diego resident's discount at a golf course.
Geragos also argued Peterson normally traveled with camping equipment and, by playing a tape of a phone conversation between Peterson and his brother, tried to show he was trying to evade the media, not police.
Still, Geragos did not explain why Peterson's alibi placed him near the area where the remains of Laci and the unborn child she had planned to name Conner were found. The defense also promised to show the fetus could have been born alive, and some critics said, failed.
Prosecutors believed Peterson killed Laci on either Dec. 23 or 24, 2002, and used concrete anchors to sink her body in the bay. They theorized that the fetus was expelled from Laci's body after her death, which would explain why the bodies washed ashore separately. But the prosecution's current and tidal expert could not give a precise trajectory path for the remains.