Experts have said the dog-tracking evidence could be the most damaging to the defense theory that Laci Peterson was at home Christmas Eve morning 2002 before she vanished later that day - when Scott Peterson claims to have been fishing on San Francisco Bay.
Prosecutors say the dogs picked up Laci Peterson's scent in several places in the days after her disappearance, including the Berkeley Marina where Peterson claims to have launched his solo fishing trip.
Judge Alfred A. Delucchi decided to allow in only the evidence gathered by dogs at the marina. Prosecutors also wanted to present evidence that the dogs had detected a broken trail of scents leading from Laci Peterson's home to the warehouse where Scott Peterson kept his boat, along the boat's rim and at the marina.
Court precedent requires corroboration of any dog-tracking evidence, Delucchi said, adding that Scott Peterson has admitted to being at the marina and that the bodies of his wife and unborn son washed ashore along San Francisco Bay in April just two miles from there.
"It would be foolhardy for the court to admit this (other) evidence because it would inject a cancer into the record," Delucchi said.
Defense lawyers likened dog tracking to witchcraft, and said the canines were unreliable. Prosecutors have presented neither witnesses to the killing nor a murder weapon.
Authorities allege that Peterson, 31, murdered his pregnant wife in their Modesto home on Dec. 24, 2002, because he was having an affair with a massage therapist, then drove her to the bay and dumped her overboard from his small boat.
Jury selection is scheduled to begin Thursday, when court officials will summon an initial 200 residents for questioning. Peterson could face the death penalty if convicted.
On the topic of wiretaps, defense lawyers had argued investigators violated Peterson's attorney-client privilege when they listened to bits of conversations with his first attorney, Kirk McAllister.
Delucchi was unswayed by the arguments, saying investigators followed proper procedures when monitoring the calls and any privileged information they heard was "so minimal to be of no consequence."
During the first few months of 2003, investigators monitored about 3,000 of Peterson's calls, including 76 between the former fertilizer salesman and his first attorney.
With both sides bound by a gag order, it's unclear exactly what evidence prosecutors plan to use from the wiretaps, but authorities have maintained they followed all federal guidelines when using the listening devices.
By Brian Skoloff and Kim Curtis