Kolkata, June 22 : The Amritava Chowdhury case -- where a dead man in the Jnaneswari train accident turned out to be alive after 11 years -- has become murkier because the CBI sleuths after interrogating Chowdhury for nine hours came to know that the alleged man was missing for seven years. This has prompted the probe agency to go for Chowdhury's DNA and Ossification tests to confirm his identity. "There are some discrepancies that we have noticed during the interrogation and we are surprised about it - how can a 'simple' middle class family manipulate such secret and important documents. This is unlikely. We have also come to know that he was missing for nearly seven years after the accident. It is not clear where he was all these years. Chowdhury couldn't recollect properly," a senior CBI officer interrogating Chowdhury said. "We have also spoken to the neighbours in Kolkata and also the local people in his village and they said that he had developed some mental problems and he couldn't remember anything but he told them that he was kidnapped by the Maoists. We are not sure whether this is Amritava Chowdhury and so to confirm his identity we will go for DNA and Ossification test," the officer added. The CBI officers said the Ossification test is a process to know the exact age through bone mapping. The CBI officers also matched Chowdhury with his old photographs and got in touch with his school and college. "It is true that his photographs matched but we want to be sure about his identity. We have asked for all the documents of his school and college so that it can be corroborated with his present status," the officer said, adding that Chowdhury claimed to be an engineer but he couldn't answer some basic engineering questions. "There is something wrong and we need to find it out," the officer said. Meanwhile Chowdhury laid the blame entirely on the railway officials. Speaking to the media, Chowdhury said, "If we have taken any money unjustifiably then that will be returned with interest and my sister will quit the job if needed". When asked why they got into this conspiracy, Chowdhury said, "Why are you asking me? Ask the railway officials. I shall speak when the time comes." A 38-year-old man who was pronounced dead after the Jnaneswari train accident in 2010 was found to be alive after 11 years. The mystery unravelled when the CBI detained the man - Amritava Chowdhury from his Jorabagan house in North Kolkata on Saturday evening. The man was 27 years old at the time of the accident. Chowdhury was listed among the passengers who died in the Jnaneswari train accident -- one of the most horrific accidents allegedly engineered by the Maoists on May 28, 2010 in West Midnapore when the Mumbai-bound Jnaneswari Express derailed and had a head-on collision with a goods train in which 148 passengers died. /IANS