Testimony in Scott Peterson's (search) murder trial returned to what investigators found in his computers as prosecutors try to prove Peterson researched the San Francisco Bay before dumping his pregnant wife's body there.

Lydell Wall of the Stanislaus County Sheriff's Department testified in early August about search engine results on hard drives from computers seized from Peterson's home and office. On Thursday, he continued testifying that Peterson searched sales ads for used boats on Dec. 7-8, 2002, just weeks before his wife vanished. Peterson also searched Web sites for fishing information, currents in San Francisco Bay and details on boat ramps in the area.

Wall is due back on the stand Monday, when investigator Steven Jacobson is also set to return.

Jacobson testified earlier Thursday that he recorded numerous phone calls in which Scott Peterson may have lied about his whereabouts in the weeks after Dec. 24, 2002, when his pregnant wife vanished. But Jacobson acknowledged the wiretaps did not capture all of Peterson's calls.

According to police, Peterson often lied to friends and family members and that he pretended to be more involved in the search for his missing wife than he really was.

On Thursday, defense attorneys sought to discredit calls suggesting Peterson lied to his mother about following up on a tip that Laci might have been spotted in Longview, Wash.

On Jan. 30, 2003, Peterson talked to a reporter about the possible sighting of his missing wife. The following day, he told his mother he discussed the tip with authorities in Longview when, in reality, he hadn't talked to anyone there, according to Jacobson.

But under cross-examination Thursday, Jacobson acknowledged Peterson may have called the Longview police but the call wasn't properly recorded.

"Not every one of those calls has audio," Jacobson said.

Peterson's attorney Mark Geragos (search ) also noted authorities could not rule out the possibility that Peterson called police from telephones not being monitored.

Jacobson also testified that Peterson made a cell phone call from his Modesto home to his voicemail at 10:08 a.m. on Dec. 24. Peterson claims he had already left the area for a solo fishing trip on the bay by then.

Jacobson said cell tower information indicates he made the call from home. That's important because a neighbor has previously testified she found the Petersons' dog wandering loose near their home at 10:18 a.m., indicating Laci Peterson had already vanished, leaving little time for her to have finished cleaning the house walk the dog and get abducted — the defense's explanation.

Jacobson testified Thursday he placed cell phone calls from Peterson's home that bounced off the same cell towers that Peterson's 10:08 a.m. call did.

But Geragos pointed out Jacobson called a person, not voicemail, as Peterson did.

"It's really comparing apples and oranges, isn't it?" Geragos asked.

"No," Jacobson replied. "That is not correct."

Jacobson refused to say whether he would have gotten different results if he'd placed calls to voicemail.

Other witnesses have said determining a person's location from analyzing cell phone tower information can be unreliable.

Judge Alfred A. Delucchi (search ) said testimony next week would turn to dog-tracking evidence. Prosecutors claim search dogs picked up Laci Peterson's scent at the Berkeley marina where Peterson launched what he claims was a solo fishing trip the day she vanished.

Prosecutors allege Peterson killed his wife in their home on or around Dec. 24, 2002, then dumped her weighted body from a small boat into the bay. The badly decomposed remains of Laci Peterson (search ) and the couple's fetus washed up along a bay shore in April 2003, not far from where Peterson said he was fishing.

His defense attorneys claim he was framed after the real killer learned of his widely publicized alibi.