Sen is at present lodged in a jail in state capital Raipur following his sentencing to life term by a trial court on Dec 24 for sedition and over his links with Maoist ideologue Narayan Sanyal.
Additional Advocate General Kishore Bhaduri, representing the Chhattisgarh government, on Wednesday told the division bench of Justice T.P. Sharma and Justice R.L. Jhanwar, that Sen had strong links with the Maoists.
He said the seized documents and other evidence were sufficient for "not suspending the sentence awarded to him by the trial court".
"Sen is a doctor by profession. But during the search at his residence, we could not find the stethoscope, any medical paper or other materials that are usually found with doctors," the prosecution counsel argued.
"It's not just a simple case of a doctor engaged in social service," he told the court.
"The trial court has already convicted Sen on charges of sedition. The documents seized and the circumstances in totality qualify for the requirement for conviction on the charges of sedition," he said.
The prosecution counsel told the court that "Rupantar" - a social organisation with which Sen and his wife were closely associated - have a few members who have Maoist connections.
He sought to quote a statement by Maoist leader Gopanna in a case in Andhra Pradesh to point out that a few NGOs and social organisations have connection with the Maoists. "We have evidence to show that they are pampering them," he added.
The defence argued hat the statement of another convict Piyush Guha - from whom police seized some incriminating letters - could not be relied upon as credible evidence as he had made the statement while in police custody.
The prosecution said: "Guha was brought to the police station as he was found in possession of certain letters. During preliminary interrogation, he told the police that it was Sen who handed over Sanyal's letters to him."
"Guha's statement led the police to Sen. At the time when Guha made the statement, no first information report (FIR) was registered, hence it can't be said that he made the statement while in police custody," the prosecution argued.
The court reserved its order after Bhaduri concluded his arguments.
Noted lawyer Ram Jethmalani Jan 24 argued for Sen's bail, highlighting loopholes in the trial court verdict.
He termed Sen's conviction as "a case of no evidence" and "political prosecution".
