NOGALES, Ariz. U.S. Customs and Border Protection wont say much about how one of its officers came to shoot Angel Mendivil Perez, a 21-year-old American, in the head at the Dennis DeConcini border crossing here earlier this year.

The port of entry, which straddles a multilane road in downtown Nogales, is a busy one. On a typical day, vehicles are lined up, filled with people who cross the border to work, eat, shop or visit family. Pedestrians use a walkway near the road, sometimes waiting for hours to present identification to enter the United States. Southbound travelers usually sail through. Its not general practice for CBP to stop drivers of vehicles leaving the U.S. for Mexico unless they have a reason or theyre doing random checks.

Around 7 p.m. on Feb. 7, Mendivil Perez tried to exit the U.S. in a pickup truck with a license plate registered to a different vehicle, according to a brief statement CBP released that month .

When Mendivil Perez, who was with a male passenger, got to the crossing, CBP officers approached the truck and questioned him. During questioning, Mendivil Perez accelerated toward Mexico, according to CBPs statement. At this time, a CBP officer fired his gun. The officer and Mendivil Perezs passenger were uninjured. Mendivil Perez was shot. The truck crashed into a cement barrier a few yards into Mexico.