The man who killed six men and injured over a dozen others after storming a Quebec City mosque will be eligible for parole after 25 years after a Supreme Court struck down a Criminal Code provision on consecutive sentencing for multiple murderers.

The unanimous high court decision happened May 27 and declared unconstitutional a 2011 provision that would allow a judge, in the event of multiple murders, to impose a life sentence and parole ineligibility periods of 25 years to be served consecutively for each murder.

The killer pleaded guilty to six charges of first-degree murder in the January 2017 attack that took place at the Islamic Cultural Centre of Quebec City.

Aymen Derbali was at the mosque the night of the shooting and was critically injured.

He said he was disappointed in the Supreme Court ruling.

"When I read the decision of the Supreme Court, I felt a deep deception as a victim of this tragedy," he said, adding he was surprised by the decision.

"I was expecting this decision to be sincere because I followed the public consultation."

On this episode of What happened to..? Erica Vella speaks with Derbali about the decision and finds out how the Supreme Court ruling will impact other cases involving multiple murders in Canada.

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