Retired IPS officer Gaurab Chandra Dutta was found dead in mysterious circumstances at his flat in West Bengal's Salt Lake area Tuesday evening, police said.
According to police, Mr Dutta was found lying in a pool of blood and a note was recovered near his body.
Mr Dutta, who had solved several important cases during his tenure, had retired last year.
He used to live alone in his house, police said.
"We have started an investigation into the case," an official of the Bidhannagar police commissionerate said.