A three-member team of the forensic department, Patna, on Tuesday inspected the site in the Jawaharlal Road area, where a partially decomposed body was found on Monday.
The body is suspected to be of Nobha Chakarvarthy, a 13-year-old girl missing since September 19. Town police station inspector Jitendra Kumar accompanied the team to the spot.
After inspecting the drain, a team member said: “The body was meticulously placed in the drain after removing the slab over it.”
The forensic department team also collected fingerprints from Nobha’s home in the same area.
The investigators took samples of the missing girl’s clothes from her father Atul Chakarvarthy.
Senior superintendent of police Rajesh Kumar told The Telegraph: “The police have lodged an FIR against unknown persons in connection with the recovery of the body.”