Convicted Canadian serial killer Robert Pickton, who took female victims to his pig farm during a crime spree near Vancouver in the late 1990s and early 2000s, has died after being attacked in prison, authorities said on Wednesday. He was 74.

The Correctional Service Canada said in a statement that Pickton, an inmate at Port-Cartier Institution in Quebec, died in hospital of his injuries after an attack involving another inmate on May 19.

A 51-year-old inmate was in custody for the attack on Pickton, police spokesman Hugues Beaulieu said earlier this month.

Robert “Willie” Pickton was convicted of six counts of second-degree murder and sentenced to life in prison in 2007, with the maximum parole ineligibility period of 25 years, after being charged with the murders of 26 women.

Police began searching the Pickton farm in the Vancouver suburb of Port Coquitlam more than 22 years ago, in what would be a years-long investigation into the disappearances of dozens of women.

The remains or DNA of 33 women, many picked up from Vancouver’s Downtown Eastside area, were found on Pickton’s pig farm in Port Coquitlam, British Columbia.

He once bragged to an undercover police officer that he killed 49 women.

During his trial, prosecution witness Andrew Bellwood said Pickton told him how he strangled his victims and fed their remains to his pigs.

Health officials once issued a tainted meat advisory to neighbours who might have bought pork from Pickton’s farm, concerned the meat might have contained human remains.

Cynthia Cardinal, whose sister Georgina Papin was murdered by Pickton, said she was “overwhelmed” with happiness when she received a text message earlier this month with the news that he had been attacked. She called it “karma”.

Vancouver police were criticised for not taking the cases seriously because many of the missing were sex workers or drug users.

Canada’s correctional service said it was conducting an investigation into the attack on Pickton.

“The investigation will examine all of the facts and circumstances surrounding the assault, including whether policies and protocols were followed,” they said in the statement.

“We are mindful that this offender’s case has had a devastating impact on communities in British Columbia and across the country, including Indigenous peoples, victims and their families. Our thoughts are with them.”

Pickton’s confirmed victims were six: Sereena Abotsway, Mona Wilson, Andrea Joesbury, Brenda Ann Wolfe, Papin and Marnie Frey.

“Earlier today, I was made aware of the death of an inmate at Port-Cartier Institution,” public safety minister Dominic LeBlanc said in a statement.

“At this time, my thoughts are with the families of the victims of this individual’s heinous crimes.”

At the time of Pickton’s sentencing, British Columbia Supreme Court Justice James Williams said it was a “rare case that properly warrants the maximum period of parole ineligibility available to the court”.