I think it’s possible he is out of the country. The fact that his car was found at Dulles indicates to me he may have skipped down big time. I’m wondering if he had been saving money for a while - because he apparently was driving a 27 year old car at the time.
Even in 1990, technology wasn’t all up to speed, so I think it’s possible he may have avoided leaving a paper trail of any kind. The fact that he had experience in electronics works to his benefit, too.