At approximately 11:45 p.m., was working in a canyon near the Lower Otay Reservoir when he and other agents saw a group of about 20 illegal aliens. The agents identified themselves as Border Patrol agents and ordered the aliens to stop. The group scattered and the agents followed. Agent Santiago gave chase along the rim of the canyon, taking a narrow trail that leads to the edge of a cliff. He lost his footing on loose rock and slippery grass, and fell approximately 120 feet to his death.

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On June 6, 1994, Luis Santiago joined the U.S. Border Patrol at the Brown Field Station in the San Diego Sector, California. After entering on duty, he was sent to the Federal Law Enforcement Training Center in Glynco, Georgia. On October 18, 1994, Agent Santiago successfully graduated from the 267th Session and returned to San Diego. Agent Santiago was one week short of taking his ten month probationary examination.