FRANKFURT (Reuters) -Berlin criminal investigators and prosecutors were on Saturday studying a device found and destroyed at a residential building housing Russian news agency staff in the city’s Steglitz district, Berlin authorities said. The device was found on Friday and investigators were looking into how dangerous it had been and who it was aimed at, a Berlin police spokesman said in response to an enquiry in the morning. A statement issued jointly by the police and the city state’s prosecutor in the afternoon said the possible motivation behind placing the device was now subject of inves…