HN Sathyanarayana Rao, who retired as a Director General of Police in August, filed the defamation case months after demanding an unconditional apology from Roopa for making what he called "baseless allegations".
In July, Roopa, as the Deputy Inspector General of Police posted in the prisons department, had alleged in a report that sidelined AIADMK leader Sasikala - serving a four-year jail term for corruption - had paid for special perks in prison, which included an exclusive kitchen and relaxed visiting hours. She also referred in her report to "rumours" that a beneficiary of a fat bribe to buy Sasikala's comfort was her senior HNS Rao.
"There were rumours that 2 crore was paid for this (Sasikala's privileges) and unfortunately the allegation is against you," Roopa had said in the report she handed to her boss.
Mr Rao, who was asked to go on leave, claimed the "wild and baseless" allegations caused severe damage to his name, fame and integrity, apart from causing mental agony to him.
The Karnataka government moved Roopa to the traffic department, but she refused to take back her allegations.