Separate chargesheets are to be filed in each of these cases, the first in about one month’s time.

The confession of Koli, a necrophile, came after about a week of his interrogation in CBI custody. Since then, all his 16 victims have been identified and statements of their parents recorded.

Surendra has confessed that his first victim was a 14-year-old girl Ripa whom he killed and sexually assaulted in February 2005. After that he would kill one child every month or two. There is, however, a six-month gap in the serial killings, which the accused said was on account of the presence of labourers building a servant quarters at Moninder Singh Pandher’s house.

There are just two child murders which Koli has not confessed to and CBI officials say this could be because he is confused about the identities of his victims. There are two boys in the list of 16 identified victims, who were probably lured by him into the “killer kothi’’ since he thought they were actually girls.

The CBI also has recorded Koli’s statements on his modus operandi. He would first the lure the children into the house and then strangulate them on the first floor of the house. After sexually assaulting the bodies through the day, he would chop the bodies. The blood of the victims was drained off in a first-floor bathroom which only he used. While the torsos were thrown in the back drain, the remaining body parts were packed tightly in plastic bags and disposed of.

The CBI has has extended the remand period of Koli and Pandher for another two weeks. There is a possibility of their confessions being video-recorded. CBI sources say Pandher’s domestic help Maya Sarkar is not an accused in the case. She has said that she—as well as some other maid servants of the locality—too was lured by Koli on one or two occasions but they resisted his overtures. She has denied knowledge of the gruesome killings.

The CBI has sent the body parts and bone samples “individualised” by the AIIMS forensic team to the forensic laboratory in Hyderabad for DNA testing.