Blood curdling details have come to light on how bodies of Nithari victims were hacked into pieces before being disposed of.

The gory revelation was made by AIIMS which conducted postmortem examination on the bodies and also concluded that there were 19 skulls -- 16 complete and three damaged, official sources said in New Delhi on Tuesday.

The bodies had been cut into three pieces before being disposed of by Surendra Kohli, one of the main accused in the serial killings of women and children in Noida.

CBI sources said Koli after strangulating the victims, used to severe the head and throw it in the drain behind the house of his employer and another main accused in the case Moninder Singh Pandher, legs in the drain in its front and the torso in the drain along the main road of the house.

Sources said Kohli used to keep the viscera in a polythene bag before throwing it into the drain to prevent easy detection and identification of the victims.

The CBI has now called experts from the Bangalore-based National Institute of Mental Health and Neuro Sciences to conduct a phsyco-pathological test on Kohli, they said.

The CBI has also sent skulls and other skeletal, and bio-material remains to the Centre for DNA Fingerprinting and Diagonastics (CDFD), Hyderabad, and roped in more DNA experts to complete the profiling in the case, the sources said.

The CBI custody of Kohli and Pandher is due to expire on February eight.