This web page will help
http://foia.state.gov/masterdocs/09fam/0940021aN.pdf. Note in particular the comments about age (although it sounds as though your friend's son won't qualify here).
My advice would be to involve a US immigration lawyer at an early stage. Although it will cost $$$$ the consequences of a declined visa application will follow this guy for life, if he ever intends to travel to the US.
MD