New details have come to light about the person Scott Peterson's defense team says it believes could be responsible for the murder of his 8-months-pregnant wife, Laci Peterson (search) and their unborn son.

The defense is searching for a man named "Donnie," with no known address and a possible tie to illegal drugs, including methamphetamines (search), Fox News has learned.

Peterson's attorneys say they're also still searching for a brown van reportedly spotted in the area when Laci disappeared on Christmas Eve. They believe that Donnie and others are linked to the van.

Meanwhile, a new inconsistency has cropped up surrounding Peterson's alibi. The murder suspect has said he was on a fishing trip on Dec. 24, when Laci vanished. But Fox News has learned that on Dec. 23, the night he and Laci were last spotted together, he told his wife's sister, Amy, that he was going on a golf trip the next day.

The couple was last seen together at the Modesto beauty parlor where Amy works. While his pregnant wife sat nearby and his sister-in-law cut his hair, Peterson told Amy that he had a golf tee time the following day, Christmas Eve, and volunteered to run an errand for her on his way home from the game, Fox News has learned.

He apparently did not mention any plans to go fishing.

Meanwhile, tensions escalated as battles over personal belongings continued this weekend between the Petersons and Laci's family, the Rochas. The latest squabble was apparently over Laci's wedding ring, which Scott Peterson wants back.

In an interview with Fox News, Rocha family attorney Adam Stewart said he was retained about two months ago by Laci's mother, Sharon Rocha, to oversee the property matters in the case.

Rocha asked Stewart not to discuss the wedding ring details with Fox News. But Stewart did say that the Peterson family ignored the Rochas' repeated requests to go into Laci and Scott's Modesto (search) home to go through some of Laci's belongings.

The Rochas had a list of 22 items -- many of them of sentimental value, like her wedding dress and the crib for the unborn baby Conner -- that they wanted to retrieve.

But after her requests were ignored, she and the rest of the Rocha family grew frustrated --leading to their surprise visit on Friday to get the mementos they sought, Stewart told Fox News. 

Against the advice of their attorney and unbeknownst to the defense, the Rochas arrived at the house Friday morning and left with several carloads of belongings -- including the crib, the dress, the rocking chair in the baby's room and other items.

"Sharon's objective, at the start of all this, was to get inside the home and look at her daughter's belongings," Stewart told Fox News. "She wanted to have that time. I think she would give back everything she has of Laci's to have that time."

The incident infuriated the Petersons and their lawyers. The battle between the two families played out at least partly in the media over the weekend.

After the anguished families clashed Friday over the Rochas' removal of personal items, a new tiff arose surrounding Laci's wedding ring -- which the Peterson family wants back, according to The Modesto Bee.

The Bee reported that Scott's mother, Jackie Peterson, told the paper her son wants the wedding ring, along with another diamond ring he gave her and some diamonds that were a gift to Laci from her grandmother.

The pieces were taken to a jeweler to be combined into one ring, according to the Bee. Jackie told the newspaper that the Rochas had retrieved the items from the jeweler.

The weekend began with the spontaneous Friday morning visit by the Rochas, who tripped the house alarm and brought police to the scene.

The brouhaha over the items came hours after grisly autopsy details were leaked to the media. The court had decided to keep the report sealed, but someone shared the information.

That led both the prosecution and Laci's family to back the release of the entire autopsy report to prevent portions of it from being taken out of context.

Scott Peterson, 30, has been charged with killing his 27-year-old wife and their unborn son, Conner, in December. He has pleaded not guilty and is in prison without bail.

Police Capt. Greg Savelli told The Modesto Bee that officers responding to Friday's burglary call at the Peterson home documented the items taken and determined that they were Laci's.

Stewart told the Bee that Scott's attorneys had agreed to let Laci's mother, Sharon Rocha, comb through the house Tuesday with members of the defense team -- who wanted to photograph and videotape the process. But that plan never materialized.

Scott's mother, Jackie Peterson, told the newspaper that Rocha had "absolutely no permission to be in that house. I have a lot of empathy for Sharon, but she does not have a right to go in our house and take what she wants."

Meanwhile the issue of the autopsy reports took another turn over the weekend. The defense and prosecution initially agreed to keep the documents sealed, but leaks seen as favorable to the defense led the prosecution to request that the whole autopsy be made public.

The leaked reports indicated that Laci's unborn son Conner was found with a deep gash around his shoulders and tape around his neck.

A spokeswoman for the Rochas said they were "devastated" about hearing the details without warning on television.

Superior Court Judge Al Girolami (search) ordered that leaks stop and indicated he would consider a gag order to stop the prosecution and defense teams from talking to the media.

The judge is scheduled to hear more arguments Friday from prosecutors on the autopsy matter.

Laci was eight months pregnant when she vanished just before Christmas. Her body and that of the unborn boy washed ashore last month in San Francisco Bay, where Scott Peterson says he was fishing when his wife disappeared.

Fox News' Dan Springer, Claudia Cowan, Catherine Donaldson-Evans and the Associated Press contributed to this report.