Kumar, who in being examined since Saturday, left the CBI office at around 9.45 pm on Tuesday after a marathon grilling session of over 11 hours.
He had arrived shortly before 10.30 am at the CBI office here.
“Kumar is being questioned in connection with his role in the alleged tampering of evidence in the Saradha scam. He has been asked to appear again tomorrow,” an official told PTI.
During the day, an unidentified masked man was called in the afternoon at the CBI office. The man came out shortly after Kumar left the premises, leaving a lot of speculation among mediapersons about his identity.
Investigation officers of both Saradha chit fund scam and Rose Valley scam were also present in the marathon 11-hour questioning on Tuesday, the official said.
Kumar was examined along with former Trinamool Congress MP Kunal Ghosh for the past two days.
The ex-MP was arrested in 2013 in the Saradha scam and has been out on bail since 2016.
The questioning of Ghosh is over for the time being and he was allowed to return to Kolkata, a CBI official said.
The Kolkata Police commissioner had already spent over 24 hours in the past three days inside the highly secured CBI office here, facing questions relating to Saradha and Rose Valley chit fund scam cases.
The Supreme Court had directed Kumar to appear before the CBI and “faithfully” cooperate in the investigation of cases arising out of the Saradha chit fund scam.
The apex court chose Shillong as a neutral meeting place “to avoid all unnecessary controversy” and made it clear that Kumar would not be arrested.
The CBI moved the Supreme Court after its officials were thwarted by the Kolkata Police when they had gone to Kumar’s official residence to question him on February 3.
West Bengal chief minister Mamata Banerjee had rushed to the spot and staged a three-day ‘Save the Constitution’ sit-in against the CBI move, accusing Prime Minister Narendra Modi and BJP national president Amit Shah of plotting a “coup”.