A masters in sociology, Mr Singh, born to a bureaucrat father and a homemaker mother, was known as an outgoing officer. He kept fit and played cricket. In his four-decade-long career, he took on Maoist rebels in rural districts and gangland bosses in the city. In one of his earlier postings in Mumbai in the 1990s, Mr Singh worked with a team of officers to clean up the underworld. At the time, India"s richest city was being suffocated by gang wars, extortion and kidnappings.