Relatives of Lawrence Hong, who along with Kaiti Perras, Joshua Hunte, Zackariah Rathwell and Jordan Segura, were all killed at a house party in April of 2014, enter court in Calgary, Alta., Monday, May 16, 2016. Matthew de Grood, 24, faces five counts of first-degree murder in what has been called Calgary's worst mass murder.

Image Credit: THE CANADIAN PRESS/Jeff McIntosh

CALGARY - Friends and family sobbed and gasped with horror Monday, May 16, as they heard graphic details about how five young people at a house party were slain by a man who believed he was killing Medusas and werewolves for the son of God.

Matthew de Grood, 24, admitted in an agreed statement of facts read at the start of his first-degree murder trial that he stabbed his victims. But court heard he told police he didn't take pleasure in it.

"I stabbed people in the house," the statement quotes de Grood as telling officers.

"I just want to say that when I stabbed them, 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," he said.

"I didn't enjoy killing at all. I said sorry, but the son of God was controlling me."

De Grood's lawyer, Allan Fay, pleaded not guilty on his client's behalf. Fay told reporters he plans to argue his client was not criminally responsible for the killings.

The stabbings, in what police have called Calgary's worst mass killing, happened at a party being held to mark the end of the university school year in April 2014.

Killed were Kaitlin Perras, 23; Lawrence Hong, 27; Josh Hunter, 23; Zackariah Rathwell, 21; and Jordan Segura, 22. Hunter, Hong and Segura all attended the University of Calgary. Perras studied at Mount Royal University and Rathwell was a student at the Alberta College of Art and Design.

Prosecutor Neil Wiberg spent more than an hour reading out the agreed statement of facts that contained details from de Grood's interview with police. The judge also lifted a publication ban on material submitted by police to obtain search warrants.

The unsealed documents detailed how de Grood, the son of a high-ranking Calgary police officer, was "a good boy, kind and compassionate" until his personality began to change about a month before the stabbings.

He began spending time alone and became quiet and withdrawn. He added a number of unusual posts on Facebook, including quotes from Mega Death lyrics, quotes from the Bible and ramblings on reincarnation.

A childhood friend invited de Grood to the party. De Grood had just finished a shift at Safeway and wore his uniform. The friend noted how de Grood was acting strange. He made a number of odd rambling statements including "Obama was the Antichrist."

The agreed facts said de Grood handed his friend a clove of garlic stating that "he may need it." He also passed him a knife similar to a bread knife with a serrated blade.

Once at the party de Grood put on a pair of blue latex gloves.

De Grood told police that he felt he had to attack Rathwell, a budding young musician, before Rathwell attacked him. He told police the two had a disagreement over Buddhism. De Grood grabbed a chef's knife with a 21-centimetre blade from a knife block in the kitchen.

"I asked him to give me my space. We were walking toward the knife block, so I decided to shoot first because I didn't know what he was going to do so I stabbed him," de Grood is quoted in the unsealed documents as telling officers.

"Then the people on the couch saw and obviously started freaking out, so I killed them from left to right as quickly as I could. The girl ran into the corner so I went and stabbed her. I said I'm sorry I have to do this. Then the guy from the kitchen wasn't dead. I had to hunt him down. Then I just left."

De Grood's friend and some others had gone out to get something to eat and came back to chaos.

"He heard screams from a female believed to be Katie. This was followed by Josh running out of the house with de Grood chasing him," read the court documents.

Police received a series of 911 calls beginning at 1:22 a.m.

Documents say one of the first officers on the scene described a "large amount of blood and carnage."

"Upon entering the front door, there was panic throughout the main floor. Two male victims lying head to head on the floor were motionless in a large pool of blood. People were attending to them but they were deceased," reported the officer.

"A fourth male victim was found lying in a fetal position on a couch while a male kept pressure to the wound to his neck. This victim was also deceased."

De Grood was arrested and taken into custody a short time later and interviewed by police.

"What I did may seem atrocious but I was killing Medusas, werewolves," he told the officers.

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

The victims' families made a statement on the courthouse steps before the start of the trial in which they urged people to focus on their loved ones. De Grood's parents, Douglas and Susan de Grood, were also in court and sat in the front row.

"The priority for us during this trial is to ensure that our loved ones will be given the full and just attention that they deserve," read Greg Perras, Kaitlin's father. "All we ask is that you remember how they lived — with purpose, with life, with goodness and love for their friends and family."

The statement said the last two years have been extremely difficult, incredibly long and anxiety-ridden for the families.

"There's no such thing as a new normal that some people talk about," Perras said. "There is only existing, surviving, and a series of bitter-sweet events going forward in our families lives such as graduations, weddings and grandchildren.

"These milestones will be happy and they will be sad."

— Follow @BillGraveland on Twitter

News from © The Canadian Press , 2016