Airport officials said the man was hit two minutes after climbing a perimeter fence and entering the runway.

Investigators are probing how a person breached DIA’s fence and was killed by a plane, raising security concerns.

DENVER — Investigators have determined the cause of death of the man who was hit and killed by a Frontier Airlines flight on a runway at Denver International Airport Friday night.

In a news conference Tuesday morning, Denver medical examiner Dr. Sterling McLaren said the man died by suicide. The cause of death was injuries from the plane’s engine, McLaren said.

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The collision happened around 11:19 p.m. Friday, when Frontier Flight 4345 was departing from Denver to Los Angeles. An engine caught fire after the man was hit, and smoke entered the cabin, leading to an evacuation of the plane.

“I want to reiterate that we are extremely saddened by the incident, and express our deepest sympathies to all of those involved,” airport CEO Phil Washington said in Tuesday’s update. “This was a horrible tragedy that has affected many people.”

The plane, an Airbus A321, was carrying 224 passengers and seven crew members, Frontier said. Twelve people on the plane reported minor injuries. Five of them were taken to the hospital. Four of those people have since been released. The condition of the fifth person is unclear.

Washington said “most” of the injuries were a result of the evacuation process.

“I want to recognize the swift and professional actions of the pilots and the crew of Frontier Flight 4345, as well as our emergency responders, operations, and maintenance teams,” Washington said. “This incident could have been more serious, could have had more serious consequences, were it not for their swift action. And those who were on Frontier Flight 4345, I want to acknowledge what a difficult and scary experience you had. We know that some of you experienced injuries, and we are all very grateful that you are safe.”

> Watch a replay of Tuesday’s news conference: 

McLaren identified the man who died as Michael Mott, 41. Investigators used fingerprints to help identify him, McLaren said.

Denver Police Chief Ron Thomas said investigators are contacting family members and others who knew the man. They’re also searching for notes and electronic devices that may help them learn more about his motivations.

Investigation into how breach happened

Washington said the man climbed an 8-foot perimeter fence topped with barbed wire. He came over the fence at 11:13 p.m. and was hit two minutes later.

The airport’s investigation will include reviewing their perimeter security program, Washington said.

DIA’s security approach includes security patrols, perimeter fence inspections and technology including closed circuit television monitoring on runways and ground-based radar that monitors fence lines, Washington said. That technology captures video and thermal imaging.

Washington said at 11:10 p.m. Friday night, ground detection sensors set off an alarm. An operator reviewed the alarm and saw a herd of deer just outside the perimeter fence. They did not initially see the trespasser, Washington said. About two minutes later, they learned the person had been hit.

“Given the short time period, we were not able to intervene and prevent this person from reaching the runway,” Washington said.

Washington said there is a gulch between the fence line and the runway, so the person was briefly out of view.

“It is something that we’re looking to improve,” Washington said Tuesday. “There’s a gulch between the fence line and the runway, so we’re looking to make sure that we have line of sight in all of those areas as well.”

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Washington said the location where the person was hit is about two miles away from the DIA terminal. Thomas said investigators didn’t find a motor vehicle or bicycle on the farmland near where the man entered the runway.

Crews examined the fence after the breach and found it was intact, DIA said. Washington said the airport’s perimeter fencing meets Transportation Security Administration guidance, and the airport has received perfect scores on multiple Federal Aviation Administration safety inspections. He said the airport has been asked why the fence isn’t taller, electrified, or topped with razor wire.

“We don’t want our fence to be deadly,” Washington said. “And even if the fence was taller, we believe a motivated individual could find a way to penetrate it.”

A combination of agencies is responsible for perimeter security. Washington said people have jumped the fences before, but “all of them in the past were apprehended very, very quickly.”

Credit: 9NEWS
A view of the perimeter fence at Denver International Airport at Runway 17L.