A search dog handler testified Tuesday that her canine picked up Laci Peterson's (search) scent at the marina where Scott Peterson (search) launched what he says was a solo fishing trip the day his wife vanished.

Eloise Anderson, a dog handler with the Contra Costa County Search and Rescue team, said the Labrador named Trimble came to the Berkeley Marina (search) on Dec. 28, 2002, four days after Peterson reported his pregnant wife missing.

Anderson said Trimble found Laci's scent and followed it from the parking area, along a tree line and down a pier, where the dog stopped at a pylon at the water's edge.

The dog then "stopped, checked out over the water, the wind was coming into her face ... turned around and gave me end-of-trail indication," Anderson said.

Prosecutors allege Peterson killed his wife in their Modesto home on or around Dec. 24, 2002, then drove to the marina and dumped her body in San Francisco Bay. Her remains and those of the couple's fetus washed ashore in April 2003, not far from where Peterson launched his fishing trip.

Defense lawyers contend someone else abducted and killed Laci, then framed their client after learning his widely publicized alibi.

Judge Alfred A. Delucchi ruled during pretrial hearings that jurors would hear some, but not all, details gathered by the scent-sniffing police dogs.

Calling the details "iffy, at best," Delucchi in March tossed out prosecution claims that other dogs had detected a broken trail of Laci Peterson's scents leading from the Petersons' home to the warehouse where Scott Peterson kept his boat and along the boat's rim.

Delucchi said the marina evidence was admissible because Scott Peterson had admitted going to the marina, and the bodies washed ashore near there.

Earlier in the day, one of Anderson's supervisors testified about how dogs pick up scent and follow trails as they search for missing people.

Christopher Boyer said he collected a number of items from the Peterson home to help in the search for Laci, including a hair brush, a pink slipper and sunglasses.

Anderson said she used the sunglasses to show Laci's scent to her search dog.

On cross-examination, defense lawyers questioned the reliability of dog-tracking evidence, constantly referring to the technique, as Boyer did himself, as "scent theory" rather than science.

Defense lawyer Pat Harris noted that during a pretrial hearing, Boyer spoke of dog-tracking as "not a science. It's an art."

Boyer remained steadfast that scientific literature supports the accuracy of dog-tracking.

"You use the word theory, correct?" Harris asked.

"Yes," Boyer said.

"It's theory, right?" Harris asked again.

"I have read it as fact," Boyer replied sternly.

Boyer also acknowledged that although dogs can pick up a scent, they cannot determine how long that scent has been there or how it got there.

Harris suggested Laci may have previously been in Peterson's truck and boat, leaving behind scent the dogs may have later smelled.

"There's no way the dog can determine when that person was in the truck or the boat, is there?" Harris asked.

"No sir," Boyer said.

Harris also noted that scents can be combined if, for example, two people live together. But Boyer argued that the dogs are trained to determine which scent to track.