From the Appeal Brief, page 60.
a. Dog scent evidence.
Though Laci Peterson’s body, and the body of her unborn child, were discovered in San Francisco Bay, the state had no direct evidence that she was killed in the Peterson’s Modesto home or transported by truck to the marina. The state sought to fill this evidentiary void with dog scent evidence. Over defense objection, the state introduced dog scent evidence collected at the Berkeley Marina.
On December 28, 2002, Eloise Anderson brought her trailing dog Trimble to the Berkeley Marina. With respect to Trimble’s track record for successfully following scent trails, Anderson admitted that Trimble “does make mistakes when you ask her to perform trailing exercises.” For example, in 2001 Trimble ran two contact trails (where the dog trails someone who has actually made physical contact with the ground, such as by running) where she had failed to trail correctly. And as to vehicle trails (where the dog trails someone who has not made contact with the ground, such as a person in a car) her record was bleak. Trimble had attempted three vehicle trails and failed two of them. Nevertheless, the state introduced a vehicle trail performed by Trimble.
Anderson provided Laci’s scent to Trimble using sunglasses that had been removed from Laci’s purse, although she knew that the purse had also been handled by Scott. After scenting Trimble with the sunglasses, Trimble gave no indication of scent at several locations at the marina until she explored the vegetation near an entrance to the boat ramp. According to Anderson, Trimble alerted at the end of the pier on the west side of the boat ramp.
Anderson and Trimble were not the only team the police called to search at the Berkeley Marina. Ron Seitz, whose dog was also certified by CARDA, was called to search the marina. Seitz used one of Laci’s slippers to scent his dog. He specifically chose the slipper as opposed to the sunglasses to avoid “cross-contamination” of scent. Indeed, in sharp contrast to the sunglasses used by Anderson to scent Trimble, there was no evidence at all suggesting that Scott had handled the slipper. Seitz’s dog did not detect Laci’s scent at the Berkeley Marina.
During closing argument, the prosecutor told the jury that if it believed Trimble detected Laci’s scent at the pier it established Mr. Peterson’s guilt of capital murder, “as simple as that.”