Nilani, in police attire, had released a video on social media in which she was seen condemning the police firing in Tuticorin and terming it as pre-planned, police said.
In the video, she is seen saying that she felt ashamed to be wearing khakhi and would have gone to meet the families of the victims who were killed in the firing, if she was not busy with her commitments.
Based on a complaint, police registered cases against her under various IPC sections including 153 (wantonly provocative with intent to cause riot), and under the Information Technology Act.
A search was on for her for the last one month, police said.
On information that she was staying in her relative's house at Wellington, the police took her into custody and produced her before the judicial magistrate Soundararajan who directed that she be taken to Chennai and be produced before a court there.