thats what i was saying earlier that we see him as sweet and innocent BUT that doesnt mean anything that we dont see. fredo is the only one that could get close to michael due to him being his brother. kay knew fredo so she wouldnt think twice about seeing him there. as for him saying he didnt know, he may not of knew fully the extent of the hit but that doesnt mean he didnt know there was a hit because as far as i see it he knew and michael would find out if he had lived that could explain whye he was upset when he told ola that he lied to him. also the fact that fredo appears to be an idiot to us makes us assume that he isnt capable of organizing the hit.