A DNA expert spent half an hour Thursday verifying a fundamental fact in Scott Peterson's (search) murder trial: the remains that washed ashore along San Francisco Bay were indeed those of Laci Peterson (search) and the couple's fetus.

Angelynn Moore of the California Department of Justice said comparisons of blood and tissue samples from the badly decomposed remains matched cheek swabs from Laci Peterson's parents and blood rime lab, said he was present during Laci Peterson's autopsy on April 14, the day her body washed ashore along San Francisco Bay.

Among the items obtained from the body for analysis were four hairs, a piece of red plastic, some plant material and a 15-inch long piece of duct tape, Nelson said.

"Were you able to take a head hair sample?" asked Prosecutor Dave Harris.

"No," Nelson replied.

"Was the head present at the autopsy?" Harris asked.

"There was no head," Nelson said.

Nelson also catalogued some of the evidence found near the body -- a plastic tarp, strips of duct tape and a piece of rusty metal. But prosecutors did not solicit testimony from him on forensic results from tests of those items.

Another criminalist testified about the DNA tests that would eventually provide the identities of Laci Peterson and her fetus.

Earlier in the day, testimony focused on the painstaking procedures detectives used while searching for evidence at the Petersons' home, warehouse and storage facility.

Defense attorneys again tried to deflect suspicion, this time by pointing to a prostitute police say stole checks from Peterson's business mailbox after his pregnant wife disappeared.

Modesto police Detective Mike Hermosa testified he arrested a woman who stole personal checks from a mailbox Peterson used for his fertilizer business. Hermosa said the woman was a prostitute who stole the checks to trade for drugs with an Asian gang.

On cross-examination, defense attorney Mark Geragos (search) used the thief to try to point suspicion away from his client.

"Were you able to go and check out her alibi for the 24th?" Geragos asked, referring to the Dec. 24, 2002 date Laci was reported missing.

"No, I never did that, sir," Hermosa replied.

Harris pointed out the checks were stolen after Laci vanished, implying the woman wasn't involved in her disappearance.

Geragos then returned to his accusations that police conducted a sloppy investigation.

Veronica Holmes, a Modesto police community service officer, testified that police videotaped an interview with Scott Peterson but no batteries were put in a tape recorder, so the footage had no sound.

Holmes said she placed the tape in her drawer and "just forgot about it."

Geragos noted it was just turned over to the defense this year.

Prosecutors called a string of other detectives to testify about the extensive search for evidence and how police thoroughly documented everything, even itemizing objects not seized.

Detective David Hawn said he collected a pea-sized piece of concrete from the Peterson's dining room during a search in February 2003, but he did not elaborate on its significance.

Prosecutors claim Peterson crafted cement anchors to weight his wife's body down in San Francisco Bay after he killed her in their Modesto home.

The remains of Laci Peterson and the couple's fetus washed ashore just two miles from where Peterson claims he was fishing alone that Christmas Eve.