I doubt whether CBI would be able find out anything at Nandigram. The area has been taken over by Police and CPM-cadres. By yesterday night they must have cleared off all the proofs like shells, killed children and ladies, the rape-victims' clothes etc.
The CBI team must check the TV recordings from all the channells like Tara-Bangla, Zee etc. However, footages of Star-Ananda (which is patronized by CPM) would hardly yield anything - but that too should be checked. The CBI team would have an uphill task ahead of it.
