Transcript for New details on the fallen Border Patrol agent
now revealing new details tonight in that investigation into an incident involving two border patrol agents in south Texas. One of those agents has died. The other in critical condition. ABC's Marcus Moore in El Paso. Reporter: New details emerging tonight in the mysterious death of border protection agent Rogelio Martinez. Sources now confirming to ABC news that Martinez and his partner were found at the bottom of a 14-foot ravine, 30 miles from the Mexican partner. And that his partner, who survived, doesn't remember what happened. The FBI says both men had traumatic head injuries, but still unable to say if it was an attack or an accident. Hours after the news broke, president trump tweeting, "Border patrol officer killed. We will and must build the wall." The president has been among those who have said that the -- he described it as a brutal attack. Is he correct? I have not briefed the president. Reporter: David, the area where Martinez and his partner were found is still a crime scene tonight, as investigators search the rugged hills of the u.s./mexico border for answers.
This transcript has been automatically generated and may not be 100% accurate.