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 19th.

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.