Ya, sh!t happens. About 20 years ago I received a frantic phone call from my brother who was being detained by US Border Patrol because he, a US citizen, crossed the border into the US without proof of citizenship. His wallet was stolen by a thug, or hooker, or a drug dealer, or a liquor store owner, or a bartender while he was drunk in Tijuana. I don't know why "they" would think that a crazy white boy leaving Tijuana would not be a US citizen. He still thinks it is becuase he couldn't answer a single question they asked... in Spanish.