Under pressure after the arrest of her key aide Madan Mitra in the Saradha scam, Trinamool Congress chief Mamata Banerjee today hit out directly at Prime Minister Narendra Modi. Arguing that an image of Madan Mitra with the man who ran Saradha should not be considered proof of criminal conspiracy, Ms Banerjee asked, should the PM be arrested just because he has appeared in photographs with Sahara chief Subrata Roy?