Just his reaction to Ray and even Ray saying "You don't look like him" meaning his son. He'd have no reason to lie since he's already in jail. And his brain condition would make him the perfect patsy. Plus the fact that he's really mexican, it's Kenny Power's baseball coach. I know it's possible for two non-red heads to still have a ginger kid but if I was going to go with that angle, I'd say he has more of a chance of actually being Ray's kid. Also, Frank mentioned he got the info from one of his guys about the original rapist that Ray killed. The only other guy that's been with him since that point now is Nails and he didn't have any problems with him this episode when they were torturing that guy or driving to the meet up, so it had to be Blake. Why would Blake just give a random cop he doesn't know, a fake name of someone to kill unless he was trying to cover his own tracks? If the rapist is dead, they won't keep digging and find Blake.
Blake's also always the one that finds Frank's men dead, he's a criminal, he's into sex parties and part of the cult, he's got red hair, and the black chief could have set it all up(the DNA match) in the hopes that Ray would lose his **** again and go kill Frank. And last night, the Catalyst guy made it clear to Osip he's just not interested in Frank.
I also don't think the Mexicans have the hard drive. I'm starting to think it's Burress who's the Birdman(riot shells like cops use, showing up at Caspere's and Ray's house) and he already recovered the hard drive. The Catalyst guy is sending Frank on a wild goose chase and causing him a ton of trouble with the cartel.
