More than 80 retired civil servants have written a strong open letter on the killing of Inspector Subodh Kumar Singh at Bulandshahr in Uttar Pradesh two weeks ago. The letter - signed by former foreign secretaries like Shyam Saran and Sujatha Singh and former National Security Advisor Shiv Shankar Menon and other retired IAS, IFS and IPS officers - called for the resignation of Chief Minister Yogi Adityanath, who they say, "openly flaunts his bigotry."