Updated at 8:25 p.m. ET
The FBI says it has found no foul play in the mysterious death of a border agent beside a remote West Texas highway last November in an incident that many assumed to be a homicide, and which prompted calls for greater border security.
An autopsy released Tuesday night concluded Border Patrol Agent Rogelio Martinez died of "blunt force trauma" to his head caused by an "undetermined manner of death."
Then late Wednesday, Emmerson Buie Jr. special agent in charge of the FBI's El Paso office, which led the investigation, released a blockbuster statement: "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 Nov. 18, 2017."
The FBI says the second agent, who survived his wounds, told a dispatcher, "We ran into a culvert."
The incident happened beside Interstate 10 near the town of Van Horn, about 120 miles southeast of El Paso and about 30 miles across rugged desert from the Mexican border.
The FBI says the investigation remains open and inconclusive, but its statement counters hasty conclusions by some conservative politicians and law enforcement figures who assumed unauthorized immigrants committed a brutal murder in the lawless borderlands.
Shortly after the incident, President Trump tweeted, "Border Patrol Officer killed at Southern Border, another badly hurt. We will seek out and bring to justice those responsible. We will, and must, build the Wall!"
Sen. Ted Cruz, R-Texas, tweeted that the incident was "a stark reminder of the ongoing threat that an unsecure border poses." Texas Gov. Greg Abbott authorized a $20,000 reward for information leading to the arrest and conviction of the assailants. Brandon Judd, president of the National Border Patrol Council, the agents' union, concluded the agents were brutally beaten with rocks.
Art Del Cueto, national spokesman for the union, said Wednesday the FBI's comments were preliminary. "They're still investigating. They're being thorough. The FBI is still keeping jurisdiction, and last time I checked, the FBI doesn't investigate traffic accidents."
The FBI statement says 37 separate field offices assisted in the investigation, which included interviews with 55 medical personnel who treated Agent Martinez. As a result of the exhaustive investigation, several suspects in Portales, N.M., were charged with alien smuggling, but none were found to be connected to the death of the 36-year-old agent.
Culberson County Sheriff Oscar Carrillo, one of the first responders to the scene, told the Dallas Morning News he thought the agents could have been sideswiped by a tractor-trailer traveling along the darkened interstate.