Send my condolences along to your son.
Sadly, a similar thing happened to me in the early days of Magic (the days of ante). I practically had a problem in terms of buying cards, and had amassed a collection that had cost me about 3,000 dollars (and would be worth who-knows-how-much now). I was in high school at the time and had only started collecting a few months before. I was very into the game, needless to say, and played every day. It seemed like everyone in my school was into the game as well.
Anyway, we had a sort of magic miniconvention one Saturday at a friend's house, and I stupidly brought my entire collection with me. There were maybe 30 people there, all of whom I knew and considered friends.
At any rate, I left most of my cards in a friend's truck under a big blanket. About half way through I went out to get another deck, and of course my cards were gone.
I never played again.