The watchdog agency says in a news release that the RCMP responded to a call from the Valley View Villa in Riverton alleging an assault had occurred.
The release says an RCMP officer attempted to arrest a 49-year-old man under the provisions of the Involuntary Psychiatric Treatment Act.
Ron MacDonald, director of the serious incident team, said in an interview that he couldn't comment if force was used during the arrest as that will be part of the investigation.
The agency says during the arrest the man showed signs of medical distress, paramedics were called and the man died at the scene.
The RCMP declined to identify the deceased man, saying they are still informing family members.