Twenty first-degree murder charges against Robert Pickton were formally stayed Wednesday, ensuring the serial killer won't stand trial for the deaths of most of the women whose remains were found on his sprawling farm.

The controversial decision to leave a question mark over the women's deaths ends the lengthy criminal case against Pickton and could set the stage for victims' families and the public to learn more about why so many sex workers vanished from Vancouver's Downtown Eastside.

Pickton was convicted in December 2007 of second-degree murder for killing Georgina Papin, Mona Wilson, Sereena Abotsway, Brenda Wolfe, Marnie Frey and Andrea Joesbury, but he was also charged in the deaths of 20 other women whose remains or DNA were found on his Port Coquitlam farm.

The judge in the case split those 20 charges off for what was supposed to be a second trial, but prosecutors later said they wouldn't pursue them if Pickton's six convictions were upheld on appeal.

The Supreme Court of Canada upheld those convictions last week.

The 20 women whose cases have been stayed are: Sarah de Vries, Diane Rock, Cara Ellis, Andrea Borhaven, Kerry Koski, Wendy Crawford, Debra Lynne Jones, Tiffany Drew, Cynthia Feliks, Angela Jardine, Diana Melnick, Jacqueline McDonell, Heather Bottomley, Jennifer Furminger, Helen Hallmark, Patricia Johnson, Heather Chinnock, Tanya Holyk, Sherry Irving and Inga Hall.

The DNA of six other women was also found on the farm, but no charges were laid in their deaths: Nancy Clark, Stephanie Lane, Jacqueline Murdock, Dawn Crey, Sharon Abraham and Yvonne Boen.

Pickton once bragged to an undercover officer that he killed a total of 49 women.

But the Crown has said it won't pursue any more criminal proceedings against Pickton -- not the 20 affected by Wednesday's decision and not any others who may be linked to him in the future.

Instead, the families of those women have been asked to find comfort in knowing Pickton has received the harshest sentence available in Canada: life in prison with no possibility of parole for 25 years.

"The Crown had to carefully assess whether it was in the public interest to proceed on the remaining 20 counts, and the (Criminal Justice) Branch concluded it was not," Neil MacKenzie, a spokesman for the Crown, said outside court Wednesday after the charges were formally stayed.

"It was a difficult decision for the branch and we certainly understand that it was a difficult decision for some family members to accept. Other family members understand the decision and agree with it."

That wasn't good enough for Lillian Beaudoin, whose sister Diane Rock is among the women whose cases were stayed.

"We feel that we've been failed by the justice system," Beaudoin said in an interview. "You don't just lay all these charges and then stay them."

All the women disappeared between 1995 and 2001, some reported missing by family and others by friends.

Several were mothers whose children were in foster care or being raised by family. Their own childhoods varied from the picture-perfect to horror shows with their paths to addiction seemingly lit by a need to escape.

A stint in rehab or back on a family member's couch was always followed by descent into the darkness of the streets.

Over time, some became well-known in the Downtown Eastside for being colourful characters in a black-and-grey world. They wrote poems, raced on roller blades, were known for their jokes or attention to fashion.

Others were enigmas, vacant eyes staring back from a police mugshot their only contribution to the women's collective infamy.

Some families wanted to see Pickton win his appeal so he would stand trial for all 26 counts of murder. Others, even relatives of some women whose cases were still outstanding, hoped the end of the lengthy criminal case would finally lead to answers about why so many sex workers were allowed to disappear from Vancouver's Downtown Eastside.

Politicians have so far resisted calls for a public inquiry and police have withheld internal reviews into how they handled reports of missing women stretching back decades, citing the ongoing criminal case.

Now, with the charges stayed, Vancouver police and the RCMP say they will release the reports from their internal reviews soon, and pressure for the province to call a public inquiry has been growing.

Vancouver's mayor and even the two police forces have joined the chorus of people calling for such hearings.

Beaudoin said public hearings are needed to shed some light on how police handled their investigation of Pickton.

"I'm out to find out what led to Robert Pickton not being caught beforehand," she said, adding her sister is believed to have been the second to last victim.

British Columbia's attorney general has not said whether an inquiry will happen.

The end of the criminal case also lifts several sweeping publication bans on the case, meaning Canadians can finally hear evidence that was kept from the jury and see a number of exhibits that have until now been secret.

The includes the testimony of a woman who said Pickton took her to his farm in 1997, put her in handcuffs and tried to kill her, with the two struggling in a knife fight that put both of them in hospital.

Pickton was charged with attempted murder, but the charges were stayed in 1998. Women continued to disappear from the Downtown Eastside for another four years.

Jurors never heard the woman's story.

Soon, the court is expected to release the video of Pickton's lengthy statement to police.

Pickton was first charged with murder in 2002 after police descended on his farm and launched an exhaustive three-year search that would uncover the dismembered bodies, bones and DNA of more than two dozen women.

Within three years, Pickton was facing 27 counts of first-degree murder, although one charge involving an unidentified "Jane Doe" was eventually dropped.

Relatives and friends of the women who had disappeared from the Downtown Eastside had been trying for more than a decade to get the attention of police, but families have said they were ignored or told the women may have simply moved on to somewhere else.

Even after the Vancouver police formed a special team to review missing women files in 1998, they rejected the idea that a serial killer was hunting women in the Downtown Eastside. In 2001, the RCMP and the Vancouver police formed a joint task force to step up their investigation.

Pickton was arrested in February the following year.

Last Friday, following the Supreme Court's decision, Vancouver police offered an unequivocal apology for failing to catch Pickton sooner.

"On my behalf and on behalf of the Vancouver Police Department and all the men and women who worked on this case I would say how sorry we all are for your losses and because we did not catch this monster sooner," said the force's deputy chief Doug LePard.

When faced with the worst, we should have been better."