Robert Pickton, one of Canada's most notorious serial killers, died on Friday, 12 days after being assaulted in prison.

Pickton, an inmate at the Port Cartier institution in Quebec, was 74 years old.

For some, death brings closure, but it also leaves lingering questions about the failed police investigation involving Pickton, who was convicted in 2007 of six counts of second-degree murder but was suspected of having killed dozens of other women on his pig farm in Port Coquitlam, British Columbia.

The Canadian correctional service stated that Pickton's next of kin were notified of his death, as well as victims who had registered to be informed.

Among them was Cynthia Cardinal, whose sister Georgina Papin was one of the six women whose deaths led to Pickton's life sentence.

Pickton chose his victims from the margins of society, women from downtown Vancouver, many of whom were Indigenous. He once boasted to an undercover officer that he killed 49 women.

Cardinal said, "This will bring healing, I won’t say to all families, I will say most families."

She added, "Because they did not get their day in court, (this) is what I feel deeply saddened about. But I also feel overwhelmingly happy now."

"Finally. I can really move on and heal, and I can put this behind me."

The Canadian correctional service said an investigation is ongoing into the assault that occurred at Pickton's prison on May 19, involving another inmate.

The correctional service stated, "We recognize that the case of this offender has had a devastating impact on communities in British Columbia and across the country, including Indigenous peoples, victims, and their families. Our hearts are with them."

Frederick Deshais, a spokesperson for the Quebec provincial police, said Friday afternoon that Pickton died "in the past few hours."

He added that police are also continuing to investigate the assault, and a 51-year-old suspect has been detained.

Quebec police said last week that doctors had planned to try to wake Pickton from his coma to see if he could survive on his own after what prison authorities described as a "serious assault."

Pickton was serving a life sentence at the Port Cartier institution, about 480 kilometers northeast of Quebec City, since being transferred from Kent Institution in British Columbia about six years ago.

At the time of his sentencing in December 2007, Supreme Court Justice James Williams stated it was a "rare case that rightly justified the maximum (25 years) for the period of ineligibility for parole available to the court."

In addition to Papin, Pickton was convicted of killing Serena Abbotsway, Mona Wilson, Andrea Josbury, Brenda Ann Wolfe, and Marnie Fry.

However, remains or DNA of 33 women were found on his farm.

One of them was Stephanie Lynn, who was in her twenties when she disappeared.

Her mother, Michelle Beaulieu, expressed overwhelming happiness at Pickton's death.

She added, "I lived 28 years without my daughter, and I know this monster killed her, and there was no justice for her in any way. So I am elated, I am happy."

She attended a gathering at CRAB Park near downtown east in honor of Pickton's victims.

Beaulieu said that since losing Lynn, "my life has not been about my daughter; it has been about Pickton."

"His death was justice."

Lorelei Williams, whose cousin Tanya Holyk's DNA was also found on the farm, said at CRAB Park that she was "overwhelmed with joy" at Pickton's death.

Pickton was only arrested in 2002 when RCMP officers were executing a search warrant for illegal firearms on his farm. They found remains and belongings of missing sex workers.

Then police began searching the property in what would be an investigation lasting years.

The Vancouver police faced criticism for not taking the case seriously because many of the missing were sex workers or drug users, and in 2014, the investigation's failure resulted in a $50,000 settlement for the victims' children who sued all three levels of government, the City of Vancouver, and the RCMP.

Pickton - who was known as "Willie" - became eligible for day parole in February, which sparked outrage among advocates, politicians, and victims' relatives who criticized the Canadian justice system, saying he should never be released.

In British Columbia, Premier David Eby said on Friday that it was a difficult day for all those affected by "Pickton's horrific crimes."

Eby added at an unrelated news conference on Friday, "I’m sure this will close some matters. For others, it opens old wounds."

"I want to take this moment to reflect on the fact that Pickton preyed on the most vulnerable people in our society, people who were labeled as less than equal, unworthy, and was able to kill so many individuals simply due to his profile of the people he chose to victimize."

He ended his remarks by saying, "What a fate."

Sue Brown, director of advocacy for the non-profit organization "Justice for Girls," stated that while some saw Pickton's death as a moment of closure, it also closed "another potential door to answers."

Brown, whose group is among those fighting in court to preserve evidence in the Pickton case, said, "There may be some sense of relief, but I know for some there are still many unanswered questions."

The RCMP requested to dispose of approximately 14,000 pieces of evidence collected in the investigation, stating they take up a lot of space and continue to increase costs.

Brown stated, "(Pickton's death) makes material evidence even more important, after now having passed someone who had personal knowledge of what happened on Pickton's farm and (what) may have happened to many of those women."

"All his knowledge has gone with him. Therefore, I think this makes the push to preserve evidence all the more urgent."

Lawyer Jason Gratl, representing several families of Pickton's victims in nine lawsuits against Pickton and his brother David Pickton, declined to comment on behalf of his clients.

Daryl Bleckas, a former prison judge at Kent Institution who later became the chairman of the British Columbia legislature, told Canadian press last week that Pickton was a potential target for others in prison because of his bad reputation and small stature.

Bleckas stated he had been aware of Pickton since his time at Kent and described him as "short and frail... five feet nothing."

"Have you ever seen Willie Pickton? ... Something weighing a hundred pounds, he’s not a big man."