The Army has concluded that Spc. Enrique Roman-Martinez’s death was a homicide, but the cause of death remains undetermined because only his head was available for examination, according to the Division of Forensic Pathology at East Carolina University’s Brody School of Medicine.

The soldier had been decapitated and dismembered, officials said. “A positive identification was made using the soldier’s dental records,” the report stated. Martinez, 21, was a member of the 82nd Airborne Division. His remains were washed ashore on Shackleford Banks Inlet of the Cape Lookout National Seashore.

A $25,000 reward has been offered for tips leading to the arrest and conviction of those responsible for his death, the Army said. The Army Criminal Investigation Command continues to probe the case.