The families of the five young people stabbed to death by Matthew de Grood at a Calgary house party say they will "never fully heal" after de Grood was found not criminally responsible for the killings.

"The finding of NCR will be a recurring nightmare for our families," said Miles Hong, the brother of Lawrence Hong, 27, who was killed along with Joshua Hunter, 23, Kaitlin Perras, 23, Zackariah Rathwell, 21, and Jordan Segura, 22, in April 2014.

"There will be no peace for us. Our wounds will never fully heal."

The NCR decision means de Grood will be sent to a psychiatric facility for treatment rather than a prison, with periodic reviews conducted by a board, which includes two judges, psychiatrists and community members.

Zackariah Rathwell, 21, Lawrence Hong, 27, Kaitlin Perras, 23, ​Jordan Segura, 22, and Joshua Hunter, 23, died after Matthew de Grood stabbed them at a party in Calgary's Brentwood community in 2014. (Facebook)

De Grood could also be labelled with the high-risk NCR designation, which would mean longer periods between reviews and harsher restrictions on his movements.

The Crown will determine whether to make a high-risk NCR application after de Grood undergoes his first mental health review 90 days from now, prosecutor Neil Wiberg told reporters.

"When that comes out in August, I'll take a look at that and then a determination will be made," he said.

Miles Hong said the families hope that will happen, as each hearing will re-open the wounds and force them to wonder again about the fate of the man who killed their loved ones.

Gregg Perras, father of Kaiti Perras, said the families' ordeals with the legal system are far from over.

'It's not over, this isn't the end'. Families of 5 killed by Matthew <a href="https://twitter.com/hashtag/deGrood?src=hash">#deGrood</a> speak emotionally outside court <a href="https://t.co/XmkuSWpPZS">https://t.co/XmkuSWpPZS</a> —@CBCNews

"These families all have a life sentence now," he said.

"Our life sentence is to, every year, go to the mental health review board and try to make sure that this dangerous offender never gets out and has a chance to hurt anyone else."

'Sorry from the bottom of my heart'

Earlier Wednesday, Justice Eric Macklin deemed Matthew de Grood to be NCR on all five counts of first-degree murder.

There was silence in the courtroom as Macklin delivered his decision, and then defence lawyer Allan Fay teared up as he revealed de Grood had prepared a written statement, which he read aloud.

"I am sorry from the bottom of my heart.... I will take responsibility for my illness," Fay said, reading from de Grood's statement, as family members of the deceased openly wept in the gallery.

Matthew de Grood, shown on the left on the first day of his murder trial on May 16, 2016, and on the right in happier days. (Sketch by Janice Fletcher/Photo by Canadian Press)

De Grood's statement went on to say that he recognized the "immense suffering" his actions have caused and to tell the families they didn't deserve the pain and loss they have endured.

Macklin told the families they had shown courage, dignity and grace in the face of unspeakable grief and pain, and had honoured their memories of their lost loved ones.

During the trial, the court heard de Grood thought he was an alien who was fighting vampires.

On Tuesday, lawyers for both the Crown and defence agreed that de Grood was in a psychotic state and unable to distinguish between right and wrong at the time of the killings.

"The psychotic episode, which affected his mind, did not reduce his effectiveness as a killing machine," noted prosecutor Wiberg in his closing statements.

Not criminally responsible

Observers believed it was unlikely de Grood would be found guilty for murder in the five deaths, despite the relative scarcity of cases where the accused is found not criminally responsible.

Nationally, about 1 out of 1,000 criminal cases are found to be NCR, according to forensic psychologist Patrick Baillie. Of those, fewer than 10 per cent are for violent offences.

In Alberta, between April 1, 2013, and March 31, 2014, 19 people were found to be not criminally responsible. In the next 12 months, another 19 people were deemed NCR.

Statistics from Alberta Justice show there are approximately 60,000 criminal arrests in the province each year.

Impact on families

The trial has taken its toll on the family members of the five who were killed.

In an unusual move, the judge earlier allowed them to address the court, reading emotional statements and paying tribute to their loved ones and sharing the impact the slayings have had.Speaking to CBC News, Jordan Segura's mother, Patty Segura, said the trial has been a "waste of time" that's been difficult on her.

"I'm not going to carry it with me every day," she said. "I'll always have Jordan in my heart, but I won't always have this legal stuff with me every day. I'll go find some happiness somewhere."