(CNN)The mystery surrounding the death of US Border Patrol agent Rogelio "Roger" Martinez continues.
Border Patrol agent's mysterious death came from head injuries
A medical examiner in Texas said Tuesday that Martinez died from blunt injuries to the head but the manner of Martinez's death is "undetermined."
Martinez, 36, died in November after being found severely injured near Van Horn in West Texas.
According to an autopsy report released by the El Paso County Medical Examiner's Office, Martinez had fractures to his skull, right jaw, upper ribs and his right collarbone.
The agent had cuts in his scalp, the report says, and a large bruise on his right shoulder. There was also a purple discoloration behind his right ear.
Another agent, Stephen "Michael" Garland, was injured and reportedly told investigators he could not remember anything about what happened.
Martinez and Garland were found near a concrete-lined culvert under Interstate 10, about 12 miles east of Van Horn, late on the evening of November 18. Martinez died in a hospital in El Paso a few hours later.
The FBI has been investigating several possibilities, including an accident, an attack or an altercation between the two agents, a Department of Justice official with knowledge of the investigation said.
Jeanette Harper, an FBI special agent and spokeswoman for the agency's El Paso office, said in December that despite investigators conducting more than 100 interviews, all possibilities remain open.
The FBI and the state of Texas have offered a $70,000 reward for information in this case.
CNN reached out to US Customs and Border Protection for comment on the autopsy results but didn't get an immediate response.
Van Horn is about 120 miles east of El Paso.