FERGUS FALLS, Minn. (AP) — Authorities say an Otter Tail County deputy was under the influence of the powerful painkiller fentanyl while involved in a high-speed chase that ended in a deadly crash.

Deputy Kelly Backman is charged with misconduct by a public officer and driving while intoxicated for the October incident that killed a couple in Fergus Falls.

Court documents show that Backman was in pursuit of a minivan driven by a man who was the subject of a drug investigation. The minivan allegedly ran a stop sign and caused a crash that killed 72-year-old Steve Christianson and his 71-year-old wife, Diane, both of Fergus Falls.