This is truly one of the most bazaar episodes in all of aviation history. AVWEB reported on it at the time and it seemed to be something out of a cheap, technology devoid TV episode plot, the story, not the AVWEB report.
IIRC he lost it in maneuvering, though may have been suicidal anyway.
(Many pilot suicides over the years.)
KOIN is a Portland OR TV station, not WA. 
When you listen to the audio, he had no intention of landing anywhere. He gave no indication of anything other than crashing when he was finished.
Homeland Security is Air Force/Air National Guard. The navy doesn’t get involved with this. They used to maintain a scramble team at McChord AFB, just south of Seattle. I’m sure it was cost cutting to use the Portland ANG at PDX as the scramble base.
Theft is criminal. We pay the price in increased insurance and ticket costs for his act…not to mention the public cost of operating those F15s. Airport security was certainly lax.