Tenth Additional District Judge, Alipore, Uttam Kumar Nandy today reserved his judgement after hearing the lawyers.
Mitra's counsel appealed for his bail, claiming that the former minister was no more influential after losing this year's Assembly polls.
The CBI's counsel objected the bail plea, saying that "Mitra still has access to the witnesses in the case and if granted bail he will try to influence them".
Investigation into the ponzi scam, which came to light in 2013, revealed that the Saradha Group had allegedly cheated investors of Rs 1,200 crore in mainly rural areas, as per an official estimate.
Former Union minister Matang Sinh is among those arrested in the case, while several TMC functionaries, including Chief Minister Mamata Banerjee's close aide Mukul Roy, have been questioned.
The CBI took over the investigation in June 2014 on following an order of the Supreme Court.