US Pport for Venezuelan Citizen?

My uncle was born in Venezuela and moved to the US when he was a little boy. He's almost 50 now. He has had a Green Card since he was a child, but about 15-20 years ago he was arrested with a felony. I believe it was a drug felony. So he wasn't able to become a citizen. Has it been long enough for him to apply for citizenship?? He also just married a Columbian woman who is a US citizen. They are trying to travel outside of the country, and need a pport. But how would he go about applying? Does anybody know what he needs to do?