A van driver unloads luggage belonging to several passengers being detained by federal agents at the checkpoint just north of the border. The operations occur at random, unannounced times. (Mark Boster/Los Angeles Times)
U.S. Customs and Border Protection officers remove a passenger in handcuffs from a bus on southbound Interstate 5 in the border-adjacent San Ysidro section of San Diego. Federal agents say the checkpoints are a productive way to stop dangerous criminals, drug shipments and money launderers. (Mark Boster / Los Angeles Times)
Detainees stand against a barrier. Federal agents say that unless the illegal immigrants have serious criminal records or numerous immigration violations, most are returned to Mexico within a few hours. (Mark Boster / Los Angeles Times)
An agent motions a bus over. The checkpoints have been randomly deployed since the Sept. 11 terrorist attacks, with inspectors typically looking for fugitives, stolen vehicles, weapons, drugs and other contraband. Illegal immigrants became targets for arrest only a few months ago, according to immigrant rights groups and human rights organizations in Mexico (Mark Boster / Los Angeles Times)