Ibrahim Sulaiman Sait, wanted by the Madurai police in connection with last week's murder of former Dravida Munnetra Kazhagam Minister T Kiruttinan, surrendered before a Chennai court on Tuesday.
He was remanded to judicial custody and will be produced before the Madurai court on June 2.
Kiruttinan was killed when he was returning to his K K Nagar residence in Madurai after a walk on May 20.
Sait, a native of Ganapathipram locality in Madurai, is believed to have made a confidential statement before the magistrate.
Meanwhile, DMK president M Karunanidhi alleged that the Chief Minister Jayalalithaa-led All-India Anna Dravida Munnetra Kazhagam government in Tamil Nadu had acted with bias in arresting his son M K Azhagiri within 24 hours of Kiruttinan's murder.
Azhagiri, who is estranged from his father and brother M K Stalin, is in judicial custody till June 4.
Karunanidhi said it is an effort to destroy the DMK and the police has not acted on an AIADMK panchayat president's complaint that a party MLA was behind her husband's murder.