The CBI Director A P Singh will appear before the Parliament's Public Accounts Committee later today to give evidence in connection with the allocation of 2G spectrum. The PAC, headed by BJP veteran M. M. Joshi, has so far gathered evidence from former Telecom Secretaries S. S. Behura and D. S. Mathur, former TRAI chairman Pradip Baijal, former Member (Finance) of Telecom Commission Manju Madhvan and RBI Governor D. Subbarao, who was Finance Secretary when the 2G allocations were made in January 2008.Earlier, the Supreme Court asked the government to constitute a special court to deal exclusively with the 2G spectrum scam.The CBI told the apex court that it would file the first charge sheet in the 2G scam against A Raja and others under Prevention of Corruption Act for cheating and forgery by March 31st.