In what may be a major coup for the prosecution in Scott Peterson's murder trial, a police detective testified Tuesday that the defendant had talked about how to dispose of a dead body.

However, during cross examination, the detective added that his source was not very credible.

Detective Allen Brocchini (search) said Peterson, 31, had told a friend in 1995 that he would attach weights to a corpse, throw it into the ocean and allow fish to eat the remains.

Peterson said "said he would tie a bag around the neck with duct tape," Brocchini testified.

The detective said Peterson, accused of killing his pregnant wife Laci and unborn son Conner, added that "fish activity would eat away the neck and hands and the body would float up, no fingers, no teeth."

While being questioned by the defense team, Brocchini acknowledged the man called him a day after Peterson was arrested and had little credibility.

Brocchini did not explain how he learned of the 1995 conversation.

Prosecutors allege that Peterson murdered his wife, weighted her body down with concrete anchors and dumped her in San Francisco Bay (search) on or around Christmas Eve 2002.

Defense lawyers say he was fishing on the bay when Laci Peterson disappeared, and that someone else abducted her near their Modesto home as she walked the dog.

The defense said her abductors held Laci Peterson captive before killing her and dumping her body to frame Peterson.

The remains of Laci Peterson — just her torso — and her fetus washed ashore four months after she vanished just two miles from where Peterson claims to have been fishing.

Defense attorneys have attacked Brocchini's investigation as shoddily executed and designed from the start to implicate Peterson during their four days of questioning.

Brocchini, the first investigator assigned to the report that Laci Peterson had vanished, returned to the stand Tuesday. Defense lawyer Mark Geragos (search) immediately told the judge he was finished questioning Brocchini.

Prosecutor Rick Distaso then asked Brocchini about Peterson's explanation of how he would dispose of a body and about the numerous tips police received in the days after Laci vanished.

"Is it fair to say there were tips coming in that people saw Laci Peterson all over the world?" Distaso asked.

"Yes," Brocchini said.

He added that police did not follow every lead, saying that "sometimes you could tell by the tip it was a crackpot."

In his cross-examination Monday, Geragos accused Brocchini of ignoring important leads, questioning him about several tips police received early in the investigation, including one on Dec. 26, 2002, that she was being held in a storage bin about 30 miles from Modesto.

Brocchini said he knew of it, but did not have much information.

Geragos said police flew over the area with a helicopter equipped with a heat-seeking device and discovered what could have been a sign of life, but officers never searched the area.

Geragos then asked the detective about a report from police in nearby Tracy that a man of Pacific Island descent had tried to kidnap a 15-year-old girl a few days before Laci's disappearance.

Witnesses have said they saw a van with three "dark-skinned" men in the Petersons' neighborhood around the time Laci vanished. It is a detail Geragos has continually brought up in the trial as he works to create doubt and tries to show police ignored any leads that did not point to Peterson.

Brocchini said he never followed up on that tip, despite the man's description as dark-skinned.

The Associated Press contributed to this report.