Alberta's police watchdog has determined the actions of Calgary Police Service members were justified in the fatal 2018 shooting of a woman and the officers likely saved the life of the woman's son.

Police were called to a home on Penbrooke Close S.E. late in the morning of May 17, 2018 following reports of a break-in in a basement suite.

Officers determined the intruders —later determined to be a 33-year-old woman and her 17-year-old son — had barricaded themselves within the suite. The suspects did not respond to announcements from police.

Approximately 45 minutes after the arrival of police, an argument between a male and female could be heard coming from the suite and was followed a short time later by the sound of a woman screaming.

Officers used a sledgehammer to break the door and six CPS members, including a police service dog, entered the basement suite and discovered the suspects had barricaded themselves behind the door to a laundry room.

The sound of a woman in distress was heard and police used a ram to damage the door that had been blocked with a clothes dryer.

Police encountered a male holding a knife who refused to drop the weapon on command. Five rounds were fired from a 'less lethal' Arwen launcher. The suspect was struck in his legs and buttocks, fell to the ground and dropped the knife.

The female suspect grabbed the knife and proceeded to stab the other suspect — now known to be her 17-year-old son — in the chest. Two tactical team members halted the stabbing attack by firing shots from their pistols at the woman, striking her multiple times. She was pronounced dead on scene.

ASIRT, Penbrooke Meadows, knife, police shooting

The 17-year-old suspect was transported by ambulance to hospital in critical condition for treatment of two stab wounds to his upper chest.

He survived and indicated to investigators that he had no recollection of how he ended up in someone else's house.

An autopsy confirmed the 33-year-old woman died as a result of her gunshot wounds but the woman had also suffered a stab wound to her chest and four additional "sharp force injuries", likely caused by a knife, to her chest and hand. A toxicology analysis detected alcohol, methamphetamine, cocaine, opioid pain medication, and cannabis in her system.

According to the Alberta Serious Incident Response Team, the woman had an "extensive criminal history", had been in-and-out of custody since the age of 13 and was considered a "very dangerous woman" with violent tendencies. Her son had been living in Regina and was in Calgary to visit his mother who had been staying in a halfway house. He also had a significant criminal record and, at the time of the break-in, was wanted for aggravated assault.

The two had been staying in various hotels in Calgary while they searched for an apartment.

An ASIRT investigation determined the CPS members acted accordingly in their use of lethal force to prevent the woman from killing her son.

"It is impossible to make sense of a senseless event," said ASIRT officials in a statement released Thursday. "That said, the woman had, on multiple occasions prior to these events when she was sober and more stable, shared that she loved and treasured the thought of her son.

"She had wanted to do better for him and had wanted him to have a better life than she had. Addiction and mental health issues prevented that, but one has to believe that had she been in an unaltered mental state, sober, stable and rational, she would have wanted her son to live."