(CNN) As the plane he commandeered soared above picturesque western Washington State flanked by a pair of military fighter jets ready to shoot him down, Richard "Beebo" Russell had a moment of self-reflection:

"Just a broken guy," he told an air traffic controller in a now famous recording. "Got a few screws loose, I guess."

Then the wayward Horizon Airlines ground service agent added, "I never really knew it. Until now."

Indeed, as investigators seek to determine precisely how Russell absconded with the passenger-less plane and crashed it into an island in Puget Sound, killing himself, another question lingers:

Why?

There are no obvious answers, at least not yet.

A group of friends who issued a statement on behalf of Russell's family said they were "stunned and heartbroken" by the act.

The prepared statement, read aloud to reporters, described "Beebo," as Russell was known to friends and family, as having been "loved by everyone because he was kind and gentle to each person he met."

"This is a complete shock to us," the statement said.

Russell's wife, Hannah, did not attend the press conference at which the statement was read, and has made no public comment on the incident.

His social media postings are full of smiling faces and travel shots. They offer no hint of depression, anger or other factors that sometimes precede such cataclysmic events.

Jeremy Kaelin, a former co-worker, said he was shocked as news emerged that the hard-working, good-natured guy he used to joke around with at work was in the cockpit of the stolen plane.

He said it was "heartbreaking" to listen to his voice on the recording of his transmissions back and forth with the air traffic controller.

"You could tell he was in pain," said Kaelin, who worked the night shift with Russell for eight months in 2016 and his since left the airline.

"Did he screw up something bad in his own personal life? I don't know," Kaelin said. "But whatever happened to him, it really messed him up in the head and I feel sorry about that."

A current Horizon employee who worked with Russell agreed that he had shown no signs of trouble prior to Friday's incident. The worker became emotional as he described listening to Russell's voice on the recording because, he said, it was the last memory he would have.

The worker asked not to be named. He said the airline had instructed employees not to speak with the media.

Russell's online postings and news accounts from various stages of his life provide a broad-brushstroke timeline of his 29 years.

According to a bio he posted on a personal blog, he was born in Key West, Florida, and moved to Alaska as a child. He ran track and played football at Wasilla High School.

He met his future wife, Hannah, in Coos Bay, Oregon, in 2010 while both were attending school. The pair married a year later and opened a bakery together, which they ran for three years, according to Russell's blog.

In 2015, they moved to Washington state to be closer to family, and Russell landed a job at Horizon Airlines. In various videos posted online, Russell describes his job, interviews co-workers and talks about enjoying the perks of free travel.

At a press conference over the weekend, officials said Russell passed a background check at the time of his 2015 hiring that reviewed information from the past 10 years. They said such checks are done every two years following an employee's start date and that Horizon officials were unaware of any criminal charges against Russell.

Kaelin and the other Horizon worker who spoke with CNN said they were much less surprised at Russell's ability to commandeer and fly the plane than they were by the fact that he would do so in the first place.

They said flight simulators, YouTube tutorials, and even video games could tell a non-pilot much of what they needed to know in order to start the plane, take off and fly.

"We've all joked about it like, 'hey, let's just go take it for a spin.' But no one ever meant it," Kaelin recalled. "It's like, who would actually commit to doing it?"