Found out what happened to David Arnott (Criss Cross himself)
This guy got so many kudos on his performance, then never made another movie. In googling around, I found this, posted in late 2008
http://www.comeawayohumanchild.net/forum/viewtopic.php?p=1236
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My brother made only this one movie. He was offered several other parts following the filming of this but said that he found the experience too emotionally draining. His life since has been a struggle as often happens to young teenagers who find themselves with a windfall of money. He now resides in Oregon and is still trying to find himself and his place in this world. Thank you for your interest. The filming of the movie in Key West was one of the most memorable experiences in our lives.
Lucas Arnott