The attorney for Scott Peterson (search) got a police detective to concede he intentionally failed to mention a witness who could help clear the former fertilizer salesman of killing his pregnant wife.

Mark Geragos (search) used the admission Thursday by Modesto police Detective Allen Brocchini to support his contention that the investigation was a sloppily executed effort to implicate Peterson, regardless of the evidence.

However, a Modesto police spokesman told The Associated Press on Friday that the witness account is included in another detective's report that was given to defense attorneys.

The witness is a woman who recalled seeing Laci Peterson (search) at the warehouse where her husband stored his small boat.

Geragos played an audio tape on which Brocchini dictated notes from a police interview with the witness, who said Laci Peterson used the bathroom at the warehouse the day before she was reported missing.

The prosecution contends Peterson hid the recently purchased boat from his wife as part of his plan to kill her and dispose of the body in San Francisco Bay.

The woman's story provides an alternate explanation for why a strand of hair that DNA testing indicates might have come from Laci Peterson turned up on a pair of pliers in the boat. That hair is one of the few pieces of physical evidence presented by prosecutors so far.

Prosecutors allege the hair fell from Laci's body after Scott Peterson murdered her in their Modesto home on or around Christmas Eve morning, 2002. They charge he then weighted down the body and tossed it into the bay, only to have the remains of Laci and her fetus wash ashore four months later.

The bodies were found two miles from where Peterson, 31, claims he was fishing alone the day his wife vanished. Defense lawyers assert someone else abducted Laci Peterson while she walked the dog, then acted on Scott Peterson's widely publicized alibi to frame him.

Geragos implied Brocchini left out the woman's account because it did not fit with the police theory that Laci Peterson had never been near the boat.

"Can you tell me how that particular piece of information got excised out of your police report?" Geragos asked.

"I excised it," Brocchini replied.

"You did?" Geragos replied, seemingly shocked.

"I guess I did," a flustered Brocchini said.

Experts say the admission could be tough for prosecutors to counter.

"The prosecution is self-destructing much the same way we saw in the O.J. case where you have police officers just doing stupid things," said Loyola University Law Professor Laurie Levenson. "One good hit like this can cause jurors to question the remainder of the prosecution's evidence."

But Modesto police Sgt. Ed Steele offered an explanation Friday, adding that he hoped prosecutors would alert the jury when the trial resumes Monday.

"It's Geragos' spin," Steele said in an interview. "The information he's alluding to was not omitted. It was already reported. The information is actually documented in a report by another detective. That's why (Brocchini) left it out of his report."

Attorneys in the case are bound by a gag order and cannot comment outside court.

In his roaming cross examination of Brocchini Thursday, Geragos questioned every aspect of the prosecution's case — from faulty paperwork to outright omissions of critical details from witnesses.

Jurors also heard for the first time a telephone message Peterson left for his wife at 2:17 p.m. that Christmas Eve day, hours after prosecutors contend he killed her.

"Hey, beautiful," Peterson is heard saying, before asking Laci to pick up a Christmas gift basket at a Modesto store because he was stuck in traffic. "I'll see you in a bit, sweetie. Love you, bye."