That is rather like their claim that they know police are concealing evidence proving they framed him and if the police would release this evidence then they would be able to prove his innocence. You have to see all the evidence and find proof he was framed among it in order to know police have evidence they framed him and were keeping a secret.
Of course it is ludicrous to believe they would create any documents establishing they framed him let alone retain such documents. So the basis upon which they operate doesn't make sense on so many levels.
Yes it makes no sense, are they expecting to find a document, hand written by conspirators documenting the plan for the frame job, a document that was then put in the case file!

Wanting things released because they may contain information relevant to innocence doesn't make much sense to e.