According to a senior doctor at the state-run SSKM hospital, the 62-year-old former judge's condition was "stable" and needed to be under observation for a few more days before being released from the hospital.
"He is bit stable but needs to be under the observation of the doctors," the officer told PTI.
Doctors at the hospital conducted a few medical tests on the former judge during the day and the results were being awaited.
Karnan, who had been evading arrest since May 9 after the Supreme Court awarded him a six-month jail term, was arrested on the night of June 20 by a team of West Bengal CID from a private resort at Malumichampatti, about six kilometres from Coimbatore, where he was hiding for a few days.
He was brought from Chennai to Kolkata on Wednesday afternoon and was taken to the Presidency correctional home.
Karnan, who has earned the dubious distinction of being the first sitting high court judge to be awarded a jail-term by the apex court, retired from service on June 12 as a fugitive.
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