MOORHEAD, Minn. (KFGO) – Moorhead police and the Minnesota Bureau of Criminal Apprehension are investigating a former Moorhead police officer in connection with a series of vandalism incidents at his former supervisor’s home.

Court documents say the first of three incidents happened in May, 2018 at the home of Detective Lt. Brad Penas.

On May 17, Moorhead police used a search warrant at the home of former Moorhead Detective Bob Porter. Court documents say Penas told investigators it’s possible that Porter had a “personal grudge” against him that may have been the motive.

The affidavit says police obtained surveillance video that shows Porter purchasing a slingshot and ammunition from the Dilworth Walmart. Investigators believe the items purchased by Porter were “used in the commission of a crime.” Damages include a shattered glass door, damaged siding and the use of grass killer.

Porter has not been charged.

Porter’s attorney, Jade Rosenfeldt, says Porter has fully cooperated with the investigation. Rosenfeldt says “any and all options for resolution will be explored.”

Moorhead Police Capt. Deric Swenson says the department has no comment.

Porter is currently a security officer at the federal courthouse in Fargo.