A Madurai court on Wednesday dismissed the bail petition of M K Azhagiri, son of Dravida Munnetra Kazhagam president M Karunanidhi, arrested in connection with the murder of senior party leader T Kiruttinan.
First fast-track court judge Udhyanan accepted the prosecution's argument that the investigations were still in a preliminary stage.
In the course of his arguments, public prosecutor Subramaniam read out Azhagiri's letter to Karunanidhi, charging Kiruttinan with trying to create enmity within their family.
Azhagiri has been housed in the Tiruchi central jail.
The Madurai Police has also arrested former Marumalarchi Dravida Munnetra Kazhagam legislator Sivaraman, and four others -- T M Mannan, Essar Gopi, Mubarak Manthiri and 'Karate' Siva in connection with the murder.
On Tuesday Ibrahim Sait, wanted in connection with the murder, surrendered before a judicial magistrate, and was remanded to judicial custody.