OTAY MESA — A Mexican citizen suffered fatal head injuries Sunday after falling from a border fence in Otay Mesa, authorities said. The man’s age and name were not released. About 6:30 p.m. Sunday, a Border Patrol camera operator spotted three people trying to cross over a fence about a mile and a half west of the Otay Mesa Port of Entry. When a Border Patrol agent arrived, he found an individual near the base of a secondary fence, according to a statement from U.S. Customs and Border Protection. The agent was taking the person into custody when he heard a thud. He then saw an unresponsive man lying on the ground on the northern end of the fence.