Here are a couple of relevant quotes: "People crossing illegally dump their IDs for a variety of reasons. One of the main ones is that apparently, if they are caught and sent back into Mexico, Mexico will send them to their home country. If they have no ID, they stay in Mexico. That makes it easier to try to cross the border again."
"...under a huge boulder, I spotted a green passport booklet. It was completely out of sight of the dirt road I had driven in on...it was that of a male illegal alien from the Islamic Republic of Mauritania."
"...The agent informed me that the person was indeed on a terror watchlist..."
FYI, Jacumba is in the southeastern portion of San Diego County (counties in Southern California are large)