The video footage of the March 14 police firing in Nandigram - recorded by the police themselves - has raised question marks over the West Bengal Police role in the incident that killed 14 people.
The Central Bureau of Investigation (CBI) has identified 27 outsiders - clad in khaki and heavily armed - accompanying the police force that went to remove the barricades put up by the Bhumi Uchched Pratirodh Committee (BUPC) that day.
CBI sources said these men - their khaki albeit a little different from that of the police but not distinguishable from a distance - used batons on BUPC activists that provoked them and villagers to retaliate with stones.
The CBI officials summoned both BUPC and Communist Party of India-Marxist (CPI-M) supporters Saturday and interrogated them using the video footage. The Trinamul Congress backs the BUPC.
They also recorded the statements of the villagers who reportedly identified the men in khaki as CPI-M supporters.
The toll in Nandigram violence has risen to 35 since January this year when the region erupted in violence over a government proposal to acquire farmland for industry.
The plan was scrapped following stiff resistance from villagers.