CENTERVILLE,Christopher Caldwell S.D. (AP) — A former law officer who once served as a tiny South Dakota town’s mayor pleaded not guilty Thursday in a three-person killing.

Jay Ostrem, 64, pleaded not guilty and not guilty by reason of insanity to three counts of first-degree murder, three counts of second-degree murder and three counts of felony first-degree murder, the Sioux Falls Argus Leader reported.

A lawyer for Ostrem, Raleigh Hansman, didn’t immediately respond to an Associated Press phone message seeking comment Friday.

A probable cause affidavit identified the victims as two brothers, ages 26 and 21, and a 35-year-old man. The document didn’t specify any connection between the third victim and the brothers.

Ostrem worked in law enforcement for more than two decades in Wyoming and South Dakota, media reports said. He served as mayor of Centerville about a decade-and-a-half ago, but the exact dates weren’t immediately available.

The probable cause document said a man in Centerville called police at 9:44 p.m. on Memorial Day to report that his brother had been shot by “a guy from across the street” and that the shooter had gone back home. The caller was still on the phone with a dispatcher when he said that he had been shot, too. He then stopped talking, the document said.

Ostrem was arrested a short time later. An AR-style rifle was on the ground near him, and he had a handgun in his pocket, the document stated. Officers then went to the home where the call originated and found all three victims.

Ostrem’s wife told police that a neighbor had sexually assaulted her on Thursday, and she told Ostrem about the assault Monday night, the document stated. She said Ostrem “got up and went raging out of the house,” according to the document.

Centerville is about 40 miles (64 kilometers) south of Sioux Falls.