Amnesty International called Monday for an investigation into a 'pattern of unchecked human rights violations' by Indonesian police in restive Papua province. In an open letter to Papua police chief Bekto Suprapto, the London-based rights watchdog said there was evidence of unnecessary and excessive use of force, beatings and unlawful killings by police in Nabire district. 'We would like to raise to your attention a pattern of unchecked human rights violations by police in the Nabire district, Papua province, over the last year,' the letter said. 'We would like to request that you take the lead in ensuring that independent, impartial and effective investigations into these reports be conducted immediately.' It cited local witness testimony of two unlawful killings and the beatings of peaceful demonstrators and rights activists in the resource-rich province, where the Indonesian police and military stand accused of widespread abuses. 