Vancouver, B.C. — Sandra Gagnon's sister is one of the dozens of women missing in the Vancouver area, and she hoped to finally learn this week why police have charged Robert Pickton with killing 15 of them.

Mr. Pickton's lawyer, however, is expected to ask Monday for the preliminary hearing to be closed, shutting out relatives of the victims, journalists and the curious public.

It would be another blow to loved ones of the dead and missing, many of whom say police ignored them in years past when they warned that drug addicts and prostitutes from Vancouver's seamy downtown east end were disappearing, perhaps victimized by a serial killer.

"I'm shocked," Ms. Gagnon said of the possible closed courtroom. "We can't be put through any more. Enough is enough."

The case involving what police call the biggest serial killer investigation in Canadian history already has attracted international attention for its sensational elements.

Mr. Pickton and his siblings own a pig farm outside the city that has been the focus of an unprecedented search combining elements of police work, science and archaeology.

DNA and body parts of some of the 67 missing women have been found at the property, fueling rumors that the dead women may have been fed to the hogs. The rumors became so persistent that local pork sales plummeted, causing the British Columbia Pork Producers Association to ask media outlets to avoid referring to the property as "the pig farm."

The media attention is what prompted Peter Ritchie, Mr. Pickton's lawyer, to indicate he would seek a closed courtroom for the preliminary hearing, in which evidence is presented to a judge who decides if the case should go to trial.

Most preliminary hearings in Canada are under a publication ban, prohibiting details of the evidence from being reported or broadcast to prevent the tainting of a potential jury pool.

Mr. Ritchie was expected to ask for a closed hearing out of concern international media would publish the information outside of Canada. Details could then turn up in the Vancouver area on the Internet and cable or satellite television signals, he has said in the past.

He refuses requests for media interviews. Another Vancouver lawyer, Dan Burnett, said he expected opposition to a closed courtroom from Canadian and foreign media outlets and families of victims.

Mr. Pickton, 53, faces 15 first-degree murder charges, and the father of another missing woman says police have told him they found her DNA on the property. Previously, such disclosures have signaled additional murder charges against Mr. Pickton.

A task force comprising the Royal Canadian Mounted Police and the Vancouver Police Department was formed in April 2001 due to persistent complaints of inaction about the dozens of missing women, some of whom disappeared decades earlier.

In February, police raided the Pickton family property and Mr. Pickton was arrested days later. He previously was arrested in connection with a knife attack on a prostitute in March 1997. The charges, including attempted murder, were dismissed in 1998.

Relatives and friends of the missing women say police were told then about a private party house operated by Mr. Pickton and his brother frequented by prostitutes and bikers. They claim police failed to properly investigate concerns that the party house might be connected to the growing list of missing women.

At least two lawsuits have been filed by relatives of missing women against Vancouver authorities, claiming police incompetence and failure to properly investigate contributed to the continuing disappearances.

Vancouver police Chief Jamie Graham has hired a lawyer to defend the force and said last week the case was handled properly.

In a statement of defense to one of the lawsuits, filed by the family of one of his alleged victims, Mr. Pickton denied killing the woman or burying or disposing of her remains.

Mr. Ritchie has said evidence at the preliminary hearing will include more than 200 DNA samples and thousands of exhibits taken from the Pickton property in the police investigation.

More than 90 investigators continue working the 10-acre site, using construction equipment to dig up dirt that is searched for possible body parts, DNA or other evidence.