Chauhan was taken to Panchkula court, which on Tuesday granted NIA his custody till February 24 for questioning him on his alleged role in the blast in the Delhi-Lahore train that left 68 people, mostly Pakistanis, dead.
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Investigations reveal that Chauhan along with Ramchandra Kalasangra alias Ramji and Lokesh Sharma, also charged in the case, planted the explosives in the train at Old Delhi, from where the train originates, NIA's Special Prosecutor R K Handa said outside the court after the in-camera proceedings in the case.
Chauhan, believed to be a close aide of Kalsangra and Sandeep Dange, key accused in the Samjhauta case, was arrested in Noida on Delhi's outskirts on Sunday and was brought to Panchkula in Haryana today. The NIA had sought his remand for a fortnight.
"We have to unearth his complete involvement and association. During investigations, it has come to light that Chauhan underwent extensive training in handling of weapons and explosives. He took training at Karni Singh shooting range in Faridabad (Haryana) and a register seized by the CBI on August 10, 2011 has the entries of his name in that shooting range.
He also took explosives and arms training at Bagli in Dewas (Madhya Pradesh)," Handa said.
"To unearth more information about execution of the plan, preparations that were made, a thorough investigation is required, for which we have sought the remand," he said.
Chauhan, born in Mhow, was an activist of the RSS. Sources claimed that during interrogation, Chauhan had spoken about his association with the RSS and his fall out as he did not subscribe to the "new ideologies".
Lokesh Sharma, who was arrested in June 2010 on charges of participating in the criminal conspiracy of the bombing as he was present in the meeting where the alleged plot was hatched, is likely to be slapped with fresh charges for his direct involvement in the bombing, the sources said.
Meanwhile, Chauhan's counsel Anil Soni and Shailender Babbar alleged that his arrest was "politically motivated" and aimed at influencing polls in Uttar Pradesh while his family claimed that he is a farmer by profession and in "no way involved in the crime".
Handa said that Chauhan's father, who was also present in the court on Tuesday, was allowed by the court to meet his son and his defence lawyers on his plea. Radhey Shyam said that his son was summoned by the police on February 9 and after that he did not return home. "My son is a farmer by profession and he is no way involved in the crime," he told reporters outside the court.
The agency has come to conclusion that the bombs used in the blast were prepared by Dange, a right wing militant who is absconding and is alleged to be the core of attacks planned and executed since 2002.
The NIA is also looking for Dange's right hand Kalsangra in connection with the case. The sources said intense questioning of the accused was being done to ascertain the whereabouts of Dange and Kalsangra, on whom the agency has announced a cash reward of Rs 10 lakh.
After a four-year probe, the NIA had on June 20, 2011, charged Aseemanand, Sunil Joshi (now dead), Lokesh Sharma, Dange alias Parmanand and Kalasangra for hatching a criminal conspiracy which resulted in blasts in Samjhauta Express near Deewana railway station in Haryana's Panipat district, about 80 km from Delhi.
The NIA is also investigating the role of Sadhvi Pragya Thakur and Indresh Kumar in the blasts. Aseemanand and Sharma are already in judicial custody.
Apart from Ajmer Dargah blast, which claimed three lives and left 15 others injured, Aseemanand and Sharma are accused in several other blast cases across the country, including those at Hyderabad's Mecca Masjid and Malegaon.
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