The letters had allegedly been arriving in the former BCCI president's name for around six months, but were initially not taken seriously. His office received two letters on Monday, containing explicit threats to kill Ganguly and his wife and harm people close to him, according to the police complaint lodged by the former cricketer's manager. The police officer said investigators were examining the contents of the letters and trying to establish the identity and motive of the sender. We are examining the letters, their source and the courier trail to identify the person responsible," the officer said. The Kolkata Police sleuths are examining whether all the letters were sent by the same person and the reason behind the alleged threats, he said.