Dr. Brent Gould saw Mitchell in February 2012, and three months later, Mitchell used the rifle to kill two people in Burnaby, B.C., and wound another person.
The 26-year-old was later shot and killed by police, and the circumstances surrounding his death are now the subject of the inquest.
Jury members at the inquest have already heard that Mitchell had a history of mental illness and substance abuse, and that he was allowed to keep his firearms licence following the incident at the doctor's clinic.
Gould says Mitchell's behaviour at the Victoria hospital seemed reasonable, and he wasn't made aware of the man's mental health history other than what he disclosed at the ER.
He says health regions do not share medical records, but it would have been helpful in this case. (CKNW)