A press release dated 23.12.2012 on the Cyber Appellate Tribunal website states that:
Justice S K Krishnan, a retired and eminent Judge of Madras High Court assumed charge as Member (Judicial) of Cyber Appellate Tribunal, New Delhi on December 21, 2011. His appointment has been made under Section 49(1) of the Information Technology (Amendment) Act, 2008 vide Notification №2(5)/2011-Pers. 1 dated 21/12/2011.
The press release is accessible here.