Thai authorities have clear evidence that government troops were responsible for the death of a Japanese cameraman during a crackdown on opposition protests last year, a top official said Tuesday. \"After investigation it\'s very clear in the case of the Japanese cameraman (Hiroyuki Muramoto) that it was the act of government security forces. There are eyewitnesses as well as forensic evidence,\" Deputy Prime Minister Chalerm Yubamrung told the Japanese ambassador at Government House.