New Delhi, Dec 29 (IANS) Tampering with evidence in the Aarushi Talwar murder case with the victim’s vaginal swabs being swapped is one of the factors leading to the CBI seeking to close the murder as an unsolved case, a forensic expert involved in the investigations has said.

‘We were sent some slides which had the vaginal swab taken from the victim to check whether there has been a sexual assault and what came a shock was that the vaginal swab was not of the victim,’ J. Gowrishankar, director of the Centre for DNA Fingerprinting & Diagnostics, told NDTV.

‘So there has been a very clear swap that has taken place and that was something we, as an institute, had communicated to CBI (Central Bureau of Investigation) because that indicated that there was some one ensuring that the evidence has been tampered,’ he said.

Gowrishankar said that it was one of the reasons the CBI was not able to solve the case.

‘I would say it is one of the factors. When one looks back there were several points. First there was one agency investigating the case, then it was another and the chain of custody was clearly broken and that in itself is an indication that vested interests were involved,’ he said.

The CBI Wednesday sought to close Arushi Talwar’s murder as an unsolved case, citing lack of evidence over two years since the 14-year-old was found killed in her parents’ flat in suburban Noida.

‘The CBI has filed a closure report in the Ghaziabad court, citing lack of evidence in the murder,’ a CBI officer told IANS.

The CBI in September reconstituted its Special Investigation Team (SIT) last year following reports that the vaginal swabs of the teenaged victim may have been substituted.

Aarushi, the daughter of dentist parents Rajesh and Nupur Talwar, was found murdered mysteriously in their Jalvayu Vihar apartment in Noida May 16, 2008. The family’s domestic help, Hemraj, whom Noida police initially suspected for the murder, was also found killed a day later on their flat’s terrace.

Rajesh Talwar was arrested and kept behind bars for 50 days in connection with the killings, but was later let off because of lack of evidence against him.

After Rajesh Talwar was let off, the CBI arrested his medical assistant Krishna and two other domestic helps in the neighbourhood Raj Kumar and Vijay Mandal.

All of them were freed after a period of detention while the CBI continued to hunt for material evidence in the case that caused sensation in Delhi and became the talking point across the country.

The investigating agency in January this year sought permission of a Ghaziabad court to conduct narco-analysis tests on Aarushi’s parents. They underwent the tests in an Ahmedabad forensic laboratory in February.