An investigation into several law enforcement officers in South Dakota has found no evidence sufficient enough to revoke the officers' law enforcement certifications.

That finding was announced in a news release from South Dakota Attorney General's Office Chief of Staff Tim Bormann.

The complaints were filed against against Brown County Sheriff Mark Milbrandt , Brown County Chief Deputy Dave Lunzman, former Brown County Deputy Ross Erickson and Madison police officer Mathew Wollmann.

Sen. Stace Nelson, R-Fulton, filed the complaints against the men in March.

Nelson sought revocation of the men’s law enforcement certification, alleging that the officers had displayed misconduct while serving in their official capacities.

"Following a review of the initial complaint and subsequent findings of the investigation it was determined that the evidence in the cases was not sufficient to support a certification revocation of Milbrandt, Lunzman and Wollman," the release states.

Erickson voluntarily surrendered his law enforcement certification, which rendered the investigation "moot", according to the release.

The state Law Enforcement Standards and Training Commission was briefed on the cases and the decision during a commission meeting Wednesday, Nov. 13.