A judge has ordered the accused in Calgary’s worst mass murder to undergo a 30-day assessment to determine whether he is mentally fit to stand trial.

Matthew de Grood faces first-degree murder in the deaths of five young people who were stabbed to death at a house party that was being held to mark the end of the school year.

He was wearing blue coveralls when he appeared in court via closed-circuit television.

De Grood, the son of a senior Calgary police officer, appeared relaxed and leaned against a wall during the brief proceeding.

He is to return to court May 22.

He has been held in custody at the Southern Alberta Forensic Psychiatry Centre since his arrest.