05/18/2016 11:37 EDT | Updated 05/18/2016 11:59 EDT

Matthew De Grood's Lawyer Calls Psychiatrists To Testify For Defence

CALGARY — The lawyer for a Calgary man who stabbed to death five young people at an end of school house party two years ago will begin his defence today.

In an agreed statement of facts read at the beginning of his first-degree murder trial, Matthew de Grood, 24, admitted to stabbing the victims to death.

But his lawyer has pleaded not guilty on his client's behalf, saying he isn't criminally responsible.

Allan Fay said he will call two psychiatrists to testify for the defence.

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Matthew de Grood's lawyer Allan Fay has pleaded not guilty on his client's behalf. (Photo: Larry MacDougal/CP)

Fay has indicated that a first-degree murder conviction, it is necessary to prove his client not only committed the crime but that he had the necessary mental elements to do it.

The stabbings, in what police have called Calgary's worst mass killing, happened at a party in April 2014.

The evidence hasn't indicated what motivated the attack but de Grood was invited to the party by a childhood friend and mingled with guests before he grabbed a knife from the kitchen and stabbed five people.

Killed in the attack were Kaitlin Perras, 23; Lawrence Hong, 27; Josh Hunter, 23; Zackariah Rathwell, 21; and Jordan Segura, 22.

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Matthew de Grood is on trial for first-degree murder. (Photo: Facebook)

Court has heard that de Grood had been acting strangely for a few weeks before the attack and the night it occurred he had been obsessed with vampires, werewolves and the end of the world.

He said he was being controlled by the "son of God'' and that he didn't have a choice.

"I tried to do it mercifully. I aimed for their heart. They put up a struggle which made it hard but so you know it wasn't sadistic or anything,'' de Grood told police after his arrest.

A psychiatric review determined de Grood was fit to stand trial, because he understands the charges against him and is able to communicate with his lawyer.

"He's very nervous. Very sad. Sad for the people that have lost, sad for his family.''

He has been undergoing treatment at the Southern Alberta Forensic Psychiatry Centre since his arrest.

Fay said it's been a difficult time not only for the families of the victims but de Grood's family — including his father, a veteran Calgary police officer — and de Grood himself.

"He's very nervous. Very sad. Sad for the people that have lost, sad for his family,'' Fay said.

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