In the future Vagabond check out this website,

www.flightaware.com

go to the bottom left where it says "airport code" type in KBFI and then look in the arrivals section. It will not tell you the pilot but it will tell you the type of aircraft, when it landed, where it came from, when it left, and who owns the aircraft. It will get you closer to your goal, if you havent already found out. It only tracks aircraft on IFR plans but it is a great feature.