The Noida double murder case may not have been a case of honour killing after all, according to Central Bureau of Investigation sources.

Officials of the CBI had brought Dr Rajesh Talwar's compounder, Krishna, to Bengaluru in order to subject him to brain mapping and narco-analysis tests.

Prior to conducting the scientific tests, Krishna was questioned at length by both the CBI and Forensic Science Laboratory officials, a pre-requisite before the actual tests are conducted.

The officials are trying to ascertain the role played by Krishna in the Aarushi-Hemraj murder case. The indication after the initial rounds of questioning is that the theory put forth by the Noida police of the father being the killer may be wrong.

The CBI had a tough time sneaking in Krishna into the FSL complex at Madivala on Wednesday where the accused was questioned first.

Earlier, they were to take the accused to the Bowring hospital where all scientific tests are usually conducted. However, sensing trouble by the hounding television media, the accused was shifted to the FSL complex.

Sources told rediff.com that the needle of suspicion is now on Krishna and the CBI believes that he could have committed the murder. It is also said that the double murder may not have been a case of honour killing after all.

During the questioning, the CBI tried also tried to ascertain the conspiracy theory behind the killings. They suspect that Krishna could have committed the murders.

During the questioning they tried to find out whether any of the family members or hospital staff were part of the conspiracy, which finally led to the tragic deaths of Aarushi and Hemraj.

Prior to picking up Krishna, the CBI had questioned Talwar for three days and also had subjected him a lie-detector test. The CBI was not convinced that Talwar was the man who committed the murders as was being alleged by the Noida police.

Krishna is now being subject to a brain mapping test following which he will undergo a narco-analysis test in Bengaluru.

Prior to the conducting the brain mapping, Krishna was questioned for a couple of hours, late on Wednesday night.

Sources in the FSL say that the procedure may be lengthy and is expected to run into two days as the questionnaire prepared by the CBI is long and there are several aspects to be verified in this case. It is also said that Krishna may be in Bengaluru for a week at least before being taken back.

During the tests, the CBI will question Krishna about the role played by him, Talwar and the rest of the family members.

Although the CBI is quite sure that Krishna was the man to have killed the duo, they would still try and ascertain whether there was a conspiracy behind the entire episode.

The narco analysis tests are crucial to this case. Although the results of this test cannot be considered as evidence in a court of law, the CBI will make use of the leads to probe the case further.

The law demands that such tests are used as investigation tools and investigating agencies cannot draw a conclusion based only on the results of such scientific tests.