In its efforts to crack the Noida double murder case, the Central Bureau of Investigation is conducting a psychological test on Dr Rajesh Talwar, prime accused in the case.

A four-member CBI team, including a psychologist, is now conducting the test at Dasna jail in Ghaziabad, where the dentist is currently lodged.

"The four-member team includes a psychologist. So, we can safely conclude that some kind of psychological test on Dr Talwar is being conducted," a source in the prison said.

Coverage: The Aarushi muder case

In a related development, the CBI is questioning a Noida-based businessman in connection with the murder of Talwar's daughter Aarushi and servant Hemraj.

The CBI subjected Krishna, the compounder of Talwar, to a six-hour narco-analysis test in Bangalore on Thursday in connection with the case.

According to the police, the test was conducted to ascertain contradictions, if any, in his statements pertaining to the case at the Bowring hospital by the experts of the Forensic Science Laboratory.

The FSL has already conducted polygraphic test on Krishna while brain-mapping test is likely to be conducted shortly.

Krishna talks of second murderer in narco test