Caracas: Venezuelan officials say all but one of 17 miners found dead in a mass grave near where they went missing had been shot in the head.

Attorney General Luisa Ortega said Wednesday that all were quickly identified and the bodies are being returned to family members.

The government maintains the massacre in the southeastern state of Bolivar resulted from a turf war for control of a wildcat gold mine. Officials blame the killings on a gang led by an Ecuadorean national who is the target of a manhunt.

But human rights groups are calling for a thorough investigation because witnesses reported the miners were detained by armed men wearing vests bearing police insignia.

The head of Venezuela’s investigative police has said he is opening an internal probe.