Coroner Says Eldora Shooter Killed Himself

Eldora Murder Suspect Killed His Cat Before Shooting Rampage

The man who gunned down the general manager of Eldora Mountain Ski Resort committed suicide by shooting himself in the head, the Boulder County coroner said Wednesday.

Derik A. Bonestroo, 24, of Nederland, was shot by a deputy a short time after investigators said he shot Brian Mahon to death in a maintenance building at the ski area near Nederland, Colo.

“Although the sheriff’s deputy wounded Mr. Bonestroo, the wounds did not cause his death,” said coroner Thomas J. Faure.

Police also said Wednesday that Bonestroo killed his own cat before heading to the ski area with a gun.

The dead cat was found in Bonestroo's Nederland apartment when investigators executed a search warrant, looking for a motive behind the man's behavior.

"Honestly, I'm shocked," said Savannah Watson, a Nederland resident who dated Bonestroo for two years. "He was such a nice guy, a loving and friendly person.

When asked if Bonestroo had a temper, Watson said no. "He was a big guy," she said. "Most of his friends were big guys. They would wrestle around a bit, but I never saw him with anger issues at all."

Watson said she couldn't imagine why Bonestroo did what he did. She told 7NEWS that, "Sometimes there are people who feel backed into some sort of wall... by some kind of pressure in their life." She added that sometimes those people may not feel they have any other option."

Mahon's slaying happened in view of 18 to 20 ski area employees who had gathered for a morning meeting.

Boulder Undersheriff Tom Shoemaker said, "The suspect ... fired a shot into the ceiling and yelled something about religion to the employees.”

"He (the suspect) barged in and wanted to know who was a Christian and who wasn't a Christian," said Sheriff Joe Pelle.

The general manager "entered the room and asked what was going on and was shot by the suspect. The wounded employee subsequently died at the Eldora location," Shoemaker said.

A 911 call, at 7:26 a.m., alerted a deputy, on patrol in the nearby Nederland area, who saw the shooting suspect's vehicle leaving the ski area along Eldora Road, near Nederland High School.

He pursued the vehicle to Highway 119, where it turned south on the highway toward Rollinsville.

"There was a gun battle between the deputy sheriff and the suspect," Pelle told 7NEWS. He said the suspect was shot and killed in the gun battle, after he stopped his car.

The suspect's silver Infiniti sedan could be seen on the side of the highway with a tight pattern of at least four bullet holes in the windshield in front of the driver seat. There was a similar grouping in the rear window on the same side of the car.

The deputy's patrol vehicle was hit at least three times, with two shots visible in the hood and one shot in the windshield.

"Our deputy received minor injuries from flying glass when his windshield was shot," Pelle said.

"He was taking cover behind his Suburban," said Terry Bergin, a Nederland auto mechanic who said he came upon the scene on his way to work.

Bergin believed the gunfire had just ended when he drove by. He said the man was still in driver's seat and slumped over the steering wheel.

"There was no movement," Bergin said.

Boulder County Detective Commander Phil West said it appeared the gunman was shooting out the window at the officer, prior to the deputy returning fire.

The Boulder County coroner identified the suspect as Derik A. Bonestroo, 24, from Nederland.

Shoemaker said Bonestroo had a black, large-caliber, semi-automatic handgun with a high-capacity magazine and additional ammunition in the car.

The location of the final shooting was along Colo. Highway 119 near the Sundance Cafe, south of Nederland.

The sheriff's office said that when the suspect's car came to a stop, he leaned out the driver's window and began shooting at the deputy's car. The deputy exited his vehicle and went to the right rear when he used his AR-15 service rifle to fire at the suspect's car.

Bonestroo died in a hail of bullets while still sitting in the driver's seat.

The injured deputy was identified as John Seifert, a 46-year-old firearms instructor and SWAT member. He has been with the sheriff's office for about four years.

He was treated and released from Boulder Community Hospital and placed on administrative leave, a normal procedure when an officer is involved in a shooting.

Pelle said the suspect appeared to be going through some sort of emotional or mental crisis. "From discussions with roommates and co-workers he had been very emotional, not all there the last few days as far as sleep and a fixation on religion," said Pelle. Pelle said the suspect wanted to convert people who weren't Christians.

A Boulder skier told the Camera that ski resort employees and skiers who arrived early were told to gather in a bar at the ski area. He said several were crying and that one guy "collapsed in tears."

Witnesses said ski patrol members could be seen running to the pump house with first-aid equipment shortly after the shooting.

The Boulder County Bomb Squad was called in to examine a backpack in the suspect's vehicle, but nothing related to explosives was found by their remotely controlled robot.

A search warrant was executed Tuesday night at the suspect's cabin in Nederland. What was discovered is unknown, but Pelle said the suspect killed his cat prior to the shootings.

A multi-agency team is investigating the two shootings. One team is investigating the fatal shooting at the resort and interviewing witnesses and the second team is investigating the officer-involved fatal shooting on the highway.

The ski area was closed Tuesday but will reopen on Wednesday.

A message on Eldora's Web site said: "Having spent the day in shock, the employees of Eldora have decided the best thing to do to memorialize Brian is to open the ski area (Wednesday) with the slopes groomed 'Brian' perfect."

Eldora is located west of Nederland, in the mountains west of Boulder. It is a smaller Colorado ski resort, with six lifts on 660 acres, and is popular with skiers and snowboarders from Boulder and the University of Colorado.

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