EL PASO, Texas — A newly released autopsy report sheds little new light on how a U.S. Border Patrol agent was fatally injured when found beside a remote West Texas highway.

In a report issued Tuesday night, the El Paso County medical examiner's office said agent Rogelio (roh-HEE'-lee-yoh) Martinez had severe head trauma and multiple bone fractures when he and another injured agent were found on Nov. 18 in a culvert beside Interstate 10 near Van Horn, Texas. However, the report said the cause of the injuries remains "undetermined."

Some elected officials initially called the incident an attack, and FBI officials said they were investigating it as a potential assault. But a Texas sheriff among the first at the scene says a semitrailer may have hit Martinez and his partner accidentally.