RAPID CITY, S.D. (AP) — Authorities say a Rapid City woman killed in a boat crash on Pactola Reservoir died of "multiple blunt force trauma."

The Pennington County Sheriff's Office released the autopsy results Thursday as part of its investigation into the death of 33-year-old Gabrielle Fisher. Fisher was one of two people on a boat that collided with a personal watercraft on Friday, Aug. 14.

The 29-year-old personal watercraft driver, Jody Kreycik, is facing charges of boating under the influence and second-degree manslaughter. He faces up to 11 years in prison if convicted.

Pactola Reservoir is about 20 miles west of Rapid City.

Copyright 2015 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

More From KXRB