CENTENNIAL, Colo. (KDVR) — A man accused of shooting and killing his ex-wife told police he was “trying to protect his kids,” an arrest affidavit said.

David Lechner, 45, was taken into custody at East Orchard Road and South Havana Street after 8 a.m. on Thursday. Police said that he had several stab wounds and was taken to the hospital for treatment, the affidavit said.

The Arapahoe County Sheriff’s Office could not confirm whether or not the stab wounds were self-inflicted as the case is still being investigated.

According to the arrest document, Lechner “spontaneously uttered … only trying to protect his kids … felt like he had to do right by his kids to protect them … could not take it anymore,” when police took him into custody. He also told police his ex-wife had been abusing their children for years, the affidavit said.

Bystander crashed van into Lechner’s SUV

David Ottersberg was in the area for a plumbing job when heard a disturbance at Lechner’s residence at 5280 South Geneva Way.

Ottersberg looked at the home and told police he saw Lechner’s wife, Tracy, lying on the ground in the garage.

“It occurred to me that something was wrong because the way he was dressed,” Ottersberg told FOX31 in an interview. “He had his head wrapped in a scarf, his mouth wrapped. A long coat. He didn’t fit in place.”

Ottersberg told police he saw Lechner standing by Tracy with a black “boxy semi-automatic” gun in his hand, then saw Lechner shoot her in the face.

“I saw him run across the street, and when he ran across the street, jumped in his vehicle, I came and rammed the side of the vehicle, pinned him in place,” Ottersberg said. “So I hit him. He looked up, I looked up, we both looked at each other, and then he reached over and he grabbed his gun. The moment I saw him get his gun, I bailed out of the passenger side of the vehicle.”

Ottersberg wasn’t able to stop Lechner from getting away, but tells FOX31 he feels sorry for the kids in that family who just lost their mom.

“She was defenseless, Ottersberg said. “She was completely and totally defenseless when he put that bullet through her. There’s no reason for him to do that. Even if he was trying to say he was protecting himself, there was no way. He executed her.”

After Lechner was released from the hospital, he was booked into the Arapahoe County Justice Center.