A 41-year-old woman pleaded guilty to manslaughter in the case of a man who died after being injected with a mixture of fentanyl and cocaine.

Joseph Mercier, 60, died after consenting to have his partner, Morgan Churchill, inject him with the cocktail while they were doing drugs together, according to an agreed statement of facts.

Court heard within moments of receiving the injection that contained about a gram of fentanyl and a gram-and-a-half of cocaine on Dec. 22, 2022, Mercier lost consciousness and died.

Churchill, who was also under the influence at the time, never called 911 and left to go see friends.

She stayed with friends for a few days over Christmas, court heard, and returned home with a friend to find Mercier’s body was decomposing. That’s when she called 911.

Police got involved on Dec. 28, 2022, when emergency crews were called to reports of a drug overdose at a home near 79 Street and 118 Avenue.

Mercier’s death was not initially considered suspicious and a toxicology report completed in March 2023 found his cause of death to be fentanyl toxicity with the medical examiner ruling the manner of death was accidental.

A witness came forward afterwards with information that caused police to reopen the investigation.

According to the agreed statement of facts, police launched an undercover “Mr. Big” operation in early 2025 to find Mercier’s killer.

The investigation, dubbed “Operation Hinder,” landed Churchill in custody in March 2025.

Court heard she confessed to injecting Mercier with the lethal mixture and was consequently charged her with second-degree murder.

All systems were go for a trial but Churchill opted to plead guilty to the charge of manslaughter instead.

Churchill struggled with her own addiction to fentanyl and suffered trauma as a child, court heard.

“The people who are addicted to these substances are victims themselves — they lead to nothing but tragedy for the loved ones they leave behind,” Justice Steven Mandziuk said when handing down the sentence.

Mandziak pointed out “this is not a drug-dealer scenario, this is a drug-user scenario.”

Churchill was sentenced to three-and-a-half years in prison, less time served, which amounts to 525 days.

Justice Mandziuk showed some leniency because of mitigating factors, citing her plea agreement, remorse, and accountability as mitigating factors.

There were no friends of family to be seen from either side in the courtroom on Monday.

An obituary for Mercier said his remains were cremated and returned to his family in Quebec.