is opening an investigation into the disappearance of 28 miners in the southeastern jungle state of Bolívar, officials said Monday. Relatives of the missing miners have said that they were murdered Friday in a dispute over a gold claim. They have said that a gang seeking to control the claim dismembered the miners, who were operating there illegally, and disposed of the bodies. “We will conduct an objective, independent and impartial investigation,” Tarek William Saab, Venezuela’s ombudsman, said Monday, echoing a promise by the public prosecutor’s office. The state’s governor denied that any massacre had taken place.