Laci Peterson (search) may have been alive and surfing the Web as late as midmorning on the day she disappeared, Scott Peterson's lawyers suggested Monday in an attempt to raise doubts about the prosecution's timeline of the crime.

Lydell Wall of the Stanislaus County Sheriff's Department, returning to the stand for cross-examination, testified that someone used Peterson's home computer to search shopping Web sites for a scarf and a sunflower umbrella stand on Dec. 24, 2002, between 8:40 a.m. and 8:45 a.m.

"Who was the person who logged on at 8:40 a.m.?" defense lawyer Mark Geragos (search) asked.

Wall could not answer. He said authorities never asked him to determine exactly who used the home computer that morning. Laci Peterson had a tattoo of a sunflower on her ankle.

Prosecutors allege Peterson killed his pregnant wife in their Modesto home either late on Dec. 23 or early on Dec. 24, then drove to San Francisco Bay (search) and dumped her body from a boat he kept at a warehouse. The remains of Laci Peterson and her fetus washed ashore months later, not far from where Peterson claims he set out on a solo fishing trip the day his wife vanished.

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

Police allege Peterson disposed of the body on the morning of Dec. 24. With Monday's cross-examination, defense lawyers tried to show the prosecution's timeline left little time for Peterson to get rid of the body.

Prosecutors allege Peterson made a cell phone call at 10:08 a.m. Dec. 24 at or near his home. Wall testified that Peterson was browsing Web sites at his office at 10:30 a.m. the same morning. Records indicate Peterson surfed Web sites there for 26 minutes.

Former prosecutor and trial watcher Michael Cardoza said the defense was trying to establish Laci Peterson was alive in the morning.

"That really is important to their case," Cardoza said. "It really shoots holes in the prosecution's timeline."

Later, Geragos played for jurors one of many wiretapped telephone conversations made by police in the weeks after Laci Peterson vanished. Jurors last week heard only a portion of the call between Laci Peterson's brother, Brent Rocha, and Scott Peterson.

Geragos played the entire call Monday. Rocha is heard confronting Scott Peterson about his affair with Amber Frey, and Peterson admits to the affair but expresses love for his missing wife.

"You know Laci and I are happy together," Peterson says.

"I told you, Scott, the day after she left she loved you so much," Rocha says.

Peterson is heard expressing concern a volunteer center set up to help find Laci Peterson had closed after the affair became public.

"I still want to go down there and, you know, open it up and work," Peterson says. "I had nothing to do with her disappearance, Brent."