“To date none of the more than 650 interviews completed, locations searched, or evidence collected and analyzed have produced evidence that would support the existence of a scuffle, altercation, or attack on November 18, 2017,” said the release from the El Paso office of Emmerson Buie, a special agent in charge.

Rogelio Martinez died from injuries he sustained while he and his partner were responding to reports of unknown activity the night of Nov. 18 near Van Horn, a Texas town near the Mexico border about 110 miles (175 kilometers) southeast of El Paso.

Martinez’s partner radioed for help before both agents were airlifted to the hospital, where 36-year-old Martinez died a few hours later. The partner— who suffered from head injuries— was released from the hospital after several days, but told investigators he could not remember the incident.