The inquiry has heard that Lionel Desmond believed the drug had helped reduce his anxiety and depression, while virtually eliminating his suicidal thoughts.

Operations manager for the Provincial Firearms Office in New Brunswick told the inquiry she knew nothing about Desmond's post-traumatic stress disorder.

The inquiry is trying to determine how Lionel Desmond legally purchase a semi-automatic rifle even though he was diagnosed with major depression.

Police were called to Lionel Desmond's home in Oromocto, N.B., on Nov. 27, 2015, after his wife Shanna received texts from him indicating he was contemplating suicide.

Lionel Desmond's extensive military medical health records were not shared with his clinical psychotherapist.

A psychotherapist who was aware Desmond had been diagnosed with PTSD, told an inquiry Thursday she was concerned the former sniper had experienced a "single trauma."

The inquiry has heard that after Desmond was discharged, he and his wife lived in New Brunswick, where a Veterans Affairs case manager supervised his ongoing care.

Dr. Ian Slayter said Desmond's mental health issues, assessed during two meetings in the fall of 2016, were far more complex than the one diagnosis.

Desmond, a former infantryman diagnosed with PTSD in 2011, killed his family members then shot himself in the head with the same military-style carbine he had legally purchased earlier in the day.

Dr. Faisal Rahman testified that Desmond said he had come to the hospital because he was suffering from the symptoms of the disorder after having an argument with his wife Shanna.