Rajkumar, who is employed as a domestic help by Dr Anita Durrani, a family friend of the Talwars, revealed during his narco test that Krishna, a compounder employed at Dr Talwar's clinic, was upset with his employer and hence wanted to kill Aarushi.

Coverage: The Aarushi murder case

During the test Rajkumar said Hemraj had invited him, Krishna and a man named Shambhu to his quarters at Dr Talwar's home on the night of the murder. While drinking beer together, Krishna told them that he had been insulted by Dr Talwar in front of patients when he had bungled during work. He said Dr Talwar had threatened to sack him.

During their drinking session Krishna is reported to have said, 'I have been working with the doctor for so many years, how could he do that to me? I need to take revenge for that insult.'

Along with Rajkumar and Shambu Krishna went up to Aarushi's room, which strangely was not locked that night. During his narco-test Krishna had said Dr Talwar never trusted anyone and usually kept the room locked.

How and why Aarushi & Hemraj were murdered

Aarushi, Rajkumar said, threatened to expose them at which point Krishna slit her throat with a khukri. They wanted to flee the scene after killing the teenager, but Hemraj developed cold feet and threatened to expose them by going to the Talwars. Sensing danger, both Krishna and Rajkumar dragged him to the terrace and killed him, Rajkumar said during the narco-test.

Rajkumar, like Krishna, said Dr Talwar had no role to play in the murders. Last week, the Central Bureau of Investigation said Dr Talwar may be released as there is no evidence against him.

However, a source in the investigating agency told rediff.com that foul play is being suspected in Aarushi's post-mortem report. Preliminary investigation reveals the report may have been doctored. The CBI is reportedly questioning Dr Talwar about this aspect.

The narco analysis reports of both Krishna and Rajkumar speak of a fourth person present at the time of the murder. Krishna, in his test, said a man named Shambhu was present when the murders occurred. Rajkumar said Shambhu was a domestic help working for Dr Talwar's neighbour. He, however, said Shambhu had no role to play in the murders. The CBI may make Shambhu a witness in the case.

Rajkumar's narco-analysis test has put things in perspective for the CBI. The Bureau has elicited information about the location of both the weapon and the victims' mobile phones. Krishna had said Hemraj and Aarushi's mobile phones were destroyed while the khukri was flushed down the toilet.