The CBI has questioned Pattali Makkal Katchi (PMK) founder S Ramadoss and his son, former union minister Anbumani Ramadoss, in connection with the murder of a relative of Tamil Nadu minister for Commercial taxes C Ve Shanmugam, sources said.
While the senior PMK leader was questioned last evening, Anbumani Ramadoss was interrogated few days back, they said.
A relative of Shanmugam, Muruganandham, was murdered by an armed gang on May 8, 2006, when they tried to attack the former at his house in Tindivanam.
Muruganandham died while trying to save the life of Shanmugam, AIADMK strongman in Villupuram district.
The attack was following political enmity between Shanmugam and PMK.
Last month CBI had questioned Srinivasan, brother of Ramadoss, in connection with the case.
The Madras high court had in October last year ordered a CBI inquiry into the murder case.