The Palmer man accused of shooting another man in the head at an Old Glenn Highway home last week allegedly told Alaska State Troopers he was shooting to kill, after the victim wouldn't leave the residence when asked to do so.

Troopers said over the weekend that Michael Armstrong, 18, was arrested in connection with the Saturday shooting on charges of attempted murder and tampering with physical evidence, as well as two counts of assault.

A criminal complaint against Armstrong, filed Sunday by trooper Sgt. Michael Henry, identified the shooting victim as Joshua Harrison. Henry said he was told by Alanna Ridenour, a woman who arrived at Armstrong's Old Glenn Highway cabin with Harrison, that Armstrong was already at the residence Saturday and two other men -- identified in the affidavit as Trevor Arts and Devon Felton -- arrived later.

Ridenour told troopers she placed a 911 call about the shooting at about 1:30 p.m. Saturday, shortly after Armstrong stepped outside the cabin with Harrison, Arts and Felton.

"Alanna stated a short time later she heard a gunshot and the sound of something hitting the house," Henry wrote. "Then Michael came into the residence and pointed a rifle at her. Alanna pleaded with Michael to not shoot her because she has a kid."

Armstrong, Arts and Felton then left the home in a Lincoln Town Car, troopers said.

When troopers stopped the Lincoln near Mile 3 of the Old Glenn, Armstrong allegedly admitted to shooting Harrison while the four men were outside, after repeatedly telling Harrison and Ridenour to leave. Troopers also said Armstrong told them he thought he was "within his rights" to shoot Harrison.

"Michael turned around and shot Joshua in the face," Henry wrote. "(He) then stated he was going to execute Joshua, but Trevor and Devon convinced him not to. Michael further stated that he was going to shoot Alanna, but she asked him not to."

Responding medics took Harrison to Mat-Su Regional Medical Center, where troopers initially said he was in critical condition.

Armstrong said after he, Arts and Felton left the cabin, Armstrong disposed of his rifle near Mile 1.8 of Knik River Road.

"The rifle, a .303 British, was later recovered from that location by AST," Henry wrote. "There was one set of shoe tracks in the fresh snow leading away from the roadway up a hill, that were consistent with the tread pattern of Michael's shoes. The rifle was located approximately 20 yards from the road in the snow and brush."

After obtaining a search warrant for the cabin, Henry said troopers found stains consistent with blood outside and inside the residence. A bullet casing consistent with the ammunition found in the rifle was recovered from the cabin's driveway, with an impact site for a bullet -- but not the bullet itself -- found on an exterior wall of the cabin.

During a more extensive interview with Henry at the Palmer post, Armstrong said he believed Harrison had stolen a gun from him last summer, and he asked Harrison and Ridenour to leave because he was afraid he was being stolen from again. He also said he didn't call the police because "he doesn't like the police."

According to the complaint, Armstrong said at the time he shot Harrison, he was aiming for the head.

"Michael said he went into the house to shoot Alanna, because his background is to finish the fight," Henry wrote. "She asked him not to shoot her so he didn't shoot her. He saw Joshua move and went to him with the rifle, and started pointing it towards Joshua but then decided not to shoot him again. He said he figured Alanna and Joshua learned their lesson."

According to Henry, Armstrong said that he didn't think law enforcement would treat him fairly, and he planned to "disappear" after the shooting.

Court records show Armstrong was arraigned Sunday morning. He was listed in custody at the Mat-Su Pretrial Facility on Tuesday afternoon.