The criminal affidavit pertaining to a former Wyoming police sergeant now accused of triple homicide in South Dakota alleges the man charged into his neighbor’s house and shot three young men to death after leaving home in a rage. 

Jay Ostrem, 64, was a Gillette Police Department agent from 1982-2003 and retired at the rank of sergeant, Jennifer Toscana, Gillette City spokeswoman, confirmed Thursday.

He’s facing three first-degree murder charges in South Dakota, in what court documents describe as an attack on three young adult male neighbors, after Ostrem heard that one of them had made an unwanted sexual advance on his wife.

Ostrem had his first court appearance Wednesday, Dakota News Now reported.

The three victims included a 26-year-old man who’d allegedly rubbed his genitalia against Ostrem’s wife while the pair were drinking together – as Ostrem slept – in Ostrem’s home four days before the attack, according to an evidentiary affidavit filed in Turner County, South Dakota on Tuesday and sent to Cowboy State Daily on Thursday.

The other two victims included a 21-year-old man who was the first decedent’s brother, and a 35-year-old man who had a different last name from the two brothers, the affidavit says.

Neighbor Man

The wife reported to South Dakota Division of Criminal Investigation agents that the 26-year-old man was a neighbor, and that he had been over at her home while Ostrem was there sleeping on May 23.

She said the man forcibly kissed her, exposed himself to her and rubbed his genitalia against her against her wishes, the affidavit says.

When she told Ostrem about these incidents four days later, Monday, he “got up and went raging out of the house,” says the document. The wife reportedly didn’t know where he was going or if he was armed when he left. She stayed home until law enforcement arrived, she said.

The Call

The 21-year-old called 911 dispatch at about 9:44 Monday night, frantic, saying a shooting was happening at the home across from Ostrem’s, reportedly. The affidavit says the man told dispatch that his brother had been shot and killed with a shotgun.

The shooter was “a guy from across the street,” the affidavit says. The caller then said the shooter had gone back to his own home; but after some time on the phone with the dispatcher, the young man said that he, too, had been shot, reportedly.

Then the man “stopped communicating with the dispatcher,” the document says.

Shotgun Shells

A Game Fish and Parks Conservation officer responded to the home where the shooting happened, and called for backup. There he met Ostrem exiting the home through the attached garage, allegedly.

The conservation officer ordered Ostrem to stop, but Ostrem kept walking down the street. So the officer drove his vehicle that way and contacted Ostrem again near an intersection, and ordered him to get on the ground.

Ostrem complied, and let the officer know he had a gun in his pocket, the document says. An AR-style rifle allegedly lay on the ground near Ostrem. His left hand was bleeding and he reeked of alcohol, the officer reportedly observed.

Agents discovered Ostrem had a .380 handgun in his pants pocket and also had spent shotgun shell casings and at least one spent rifle casing, the affidavit says.

He was arrested.

Into The Home

Investigators entered the home where the shooting had happened and found three deceased men with apparent gunshot wounds, reportedly. They noted that Ostrem’s home is just across the street.

Use Of Force Incident

Ostrem was involved in a lethal use-of-force incident 23 years ago in Gillette, according to civil court documents, but a federal lawsuit leveled against him over it was dismissed Aug. 18, 2004. Then-U.S. District Court Judge Clarence A. Brimmer noted the use of force officers used in that incident was not found to be unreasonable.

In the early-morning hours of Nov. 3, 2001, a woman left her home to get away from her husband, Michael Owens, with whom she’d been fighting in their Gillette home, according to a civil lawsuit complaint filed in the U.S. District Court for Wyoming in 2003.

The woman’s sister reported Michael Owens to police, saying Owens was “just trying to kill her,” court documents say.

Dispatch asked Owens’ wife if Owens had a gun and she answered “yes.”

Ostrem and other Gillette police agents responded, found Owens to be driving, and followed Owens to his home. Brimmer’s order dismissing this case called it a “chase.”

One officer videotaped the events. The judge’s order says the tape “clearly reveals” the following sequence of events:

Officers ordered Owens to show his hands, as the man parked in his own driveway and rammed his pickup into the back of his garage.

Owens smashed into one of the agent’s patrol cars, then hit his garage again; then crashed into a boat seconds after one of the officers took cover behind it.

Owens then sped in reverse across the street and rammed the front door of a neighbor’s house.

Two officers (not Ostrem) were concerned for the neighbors’ safety and decided to use lethal force to stop Owens, but since they didn’t know where in the house the neighbors were, they didn’t fire.

Owens pulled forward and crashed into another car “in an apparent attempt” to hit one of the officers on scene. That officer was later found to be severely injured; he had to have two cervical discs fused, the judge’s order notes.

Then-Sgt. Ostrem saw all this and believed the officers’ lives were in danger. He ran alongside Owens’ pickup while drawing his gun; shouted commands at Owens; watched as the pickup rammed the back of the garage, and hoped Owens had knocked himself out, the order recounts.

But Owens kept driving, trying to back up again.

Ostrem emptied his entire pistol, even as Owens tried to get the truck into reverse. Owens started driving in reverse, and another officer opened fire, killing Owens.

“Our system of justice… does not deal in either sympathy or suspicion; it is built on proof,” wrote Brimmer when dismissing the case. “When the officers were threatened by Owens’ vehicle, a deadly weapon, the officers were permitted to use deadly force.”

What A Shock

Former Gillette Police Department Chief Ric Paul, who supervised Ostrem during their shared tenure, told Cowboy State Daily on Thursday that the news of Ostrem’s homicide case shocked him.

“You just can’t understand why a guy of his magnitude would do something he apparently did,” said Paul, who described Ostrem as a solid, intelligent police officer.

Though Ostrem had potentially traumatic incidents on the job, Paul said he’d insisted on Ostrem having any issues from those addressed and tracked.

“And Jay was part of those (issue briefings for the critical incidents) he was involved in,” he said.

Clair McFarland can be reached at clair@cowboystatedaily.com.