The shooting by an off-duty trooper that killed a neighbor with an airsoft gun in Butler Township last month was justified under the state’s castle doctrine law of self-dense, according to Butler County District Attorney Richard Goldinger.

Kristopher A. “Kit” Barkus, 25, was fatally shot by Trooper Brian Knirnschild about 8:40 p.m. June 6 after he showed up outside the trooper’s September Drive home.

“Legally, it was a justifiable homicide,” Goldinger said. “I don’t know how I could come to any other conclusion.”

The county’s top law enforcement officer announced his decision after reviewing findings of a two-week investigation by the state police.

“Trooper Knirnschild, because of the circumstances, acted under his belief that he had to protect himself and his family.’”

But the Barkus family discounted the findings, arguing the investigation was compromised from the beginning, said their attorney, Al Lindsay.

“The family’s concern was this was an internal investigation done by the agency under scrutiny” Lindsay said. “The family believes this shooting was not justified.”

Cpl. Dan Herr, a crime unit investigator at the Butler barracks, declined to comment on Goldinger’s decision, noting that police made no recommendation to the district attorney.

”We simply presented the facts to him to make a decision,” Herr said.

The Barkus family disputes some details of the police investigation, Lindsay said.

“The family believes the full picture of what happened is not being exposed,” he said, declining to elaborate.

Lindsay, meanwhile, suggested that a coroner’s inquest or a state attorney general’s probe would have been a better way to investigate the shooting.

“We feel there should have been an open examination of all the facts,” he said.

Lindsay would not say if the family intends to file a lawsuit in the shooting.

But Goldinger said, “I’m completely comfortable and confident that the investigation was unbiased. They did a good job in a tough situation.”