Mohan, the accused who owns a shop in Moodalapalya, allegedly drugged a 21-year-old woman customer by spraying a chemical near her face.
After she lost consciousness, he took nude pictures of her, say local media reports.
The B Com student found Mohan taking nude pictures of her when she regained consciousness. He told her that he would make the pictures public if she did not give him Rs 1 lakh, Chandra Layout police are quoted as saying.
The case came to light when the family of the victim learnt about the incident.
Before handing him over to the police, family members, locals as well as Karnataka Rakshana Vedike (KRV) activists unleashed mob justice on the pervert shop owner.