The Delhi Police have failed to identity the "unknown fingerprints" found in the room at Hotel Leela where Sunanda Pushkar, wife of Congress leader Shashi Tharoor, was found dead four years ago, derailing the investigation in the mysterious death.The police had stumbled upon the crucial evidence -- the fingerprints -- at the crime scene, but investigators could not turn this into a lead.

Read the DNA report on Sunanda Pushkar's death here.