MADISON, Wis. (AP) — No criminal charges will be filed in a boating crash that killed a windsurfer on Lake Mendota last year.

The Dane County District Attorney's Office says in a statement that the driver and two other staffers on a University of Wisconsin Lake Safety boat bear no criminal liability, and the incident doesn't rise to the level of criminal negligence.

Yu Chen was killed on May 31, 2017 when he was struck by the boat. The boat operator told investigators he saw Chen directly in front of the boat just moments before the crash and he slammed the boat into reverse.

The driver said he believed Chen was under the boat.

An autopsy determined Chen died from chop wounds to the head, neck, torso and extremities.