Premchand Sahare (54) was picked up by policemen attached to Panchpaoli police station on suspicion. According to the police, he confessed to a 1980 robbery.
Sahare said he had robbed Sohanlal Jain, a trader, of Rs 500 at knife-point at the latter's shop on April 12, 1980.
The case had remained unsolved for three decades.