Alaska Airlines said he was an employee who helps direct aircraft to gates and de-ice planes.
The suspect was identified as a 29-year-old airline mechanic and local resident who "acted alone", Troyer added, confirming that there were "no passengers on the plane" when it crashed.
Authorities initially said the man was a mechanic, but Alaska Airlines later said he was believed to be a ground service agent employed by Horizon.
The Sea-Tac Airport official Twitter account confirmed the news just after midnight, confirming that there were no passengers on the stolen plane.
"There is a protocol to not allow anyone singularly to get onboard an aircraft", Soucie said.
"It is highly fragmented", she said of the plane.
"Oh man", Rich says, "those guys will rough me up if I try and land there".
"I can't even imagine what she's going through", he said. But he also apologized to the people who cared about him, calling himself "a broken guy" with "a few screws loose".
He then said: "I wouldn't know how to land - I wasn't really planning on landing it".
Ed Troyer, of the sheriff's office, described Russell as "suicidal". It did not elaborate. We have police boats, we have everybody responding.
In addition to disrupting air traffic control, the incident also caused alarm among locals, many of whom recorded the incident. "You want me to ride the brakes in the cockpit" or 'Hey, what are you doing?' Nobody did that", said Kelly. "I've played video games before, so I know what I'm doing a little bit". "He had to know where he was going and how to get to a runway", added Furois.
Shortly before crashing into Ketron Island, Russell said he was hoping to "have this moment of serenity". The jets were armed but did not open fire, North American Aerospace Defence Command spokesman Cameron Hillier said by phone. The jets' capability was appropriate to the potential task, one of the sources said, without offering details. The F-15s were scrambled from Portland and were not involved in the crash.
"Apparently this was a plane that was stolen from SeaTac Airport".
The man, not yet named, took off late on Friday, forcing the airport to close while two fighter jets gave chase.
"I'm not quite ready to bring it down just yet", he said.
In this long-exposure photo, smoke and an orange glow are seen on Ketron Island in Washington state, early Saturday, Aug. 11, 2018 as viewed from near Steilacoom, Wash.
"Everyone was literally frozen in place, muttering about what possibly happened", he said.
"Told F-15s made it within a few minutes of theft of plane". "But holy smokes I gotta stop looking at the fuel because it's going down quick".
It wasn't immediately clear what training, if any, the man had in flying planes.
"That's their job, to be around these planes", said Brad Tilden, president and CEO of Alaska. Russell used a push-back tractor to rotate the plane 180 degrees before getting in and taxiing the aircraft. "To our knowledge, he didn't have a pilot's license".
It crashed about an hour after it was stolen and did not hit any ground structures.
Alaska Airlines on Twitter said the airplane was a turboprop Q400 airplane belonging to its sister carrier Horizon Air.
Horizon Air is part of Alaska Air Group and flies shorter routes throughout the U.S. West. "We are working background on him now", the sheriff's department tweeted. "We are giving those investigators our full support and cooperation", Tilden said in a statement.