Walkar's body was allegedly chopped up into several pieces by Poonawalla.

 what is a Narco test? 

A substance called sodium pentothal, which induces a hypnotic or drugged state in which the accused's imagination is suppressed, is injected into their bodies as part of a narco test. The accused is believed to be incapable of lying during this hypnotic condition and is supposed to reveal only accurate information.

Larger doses of sodium pentothal, a quick-acting anaesthetic with a brief half-life, are used to sedate patients before surgery.

The drug, sometimes known as a truth serum, is alleged to have been used by intelligence operatives during World War II and is believed to impair the subject's will to lie.