That’s what pre-trial “discovery” is for.
I’ve litigated RICO before. No RICO complaint, criminal or civil, will be allowed to progress to discovery without initial contemporaneous evidence for the allegations in the complaint, which if fraud-based, must be plead with particularity.
We had the evidence, however the cabal of bad actors within govt was found not to be an “enterprise” and even so, assuming en arguendo that it did constitute an enterprise, you have to show a financial gain to the “enterprise”. In this case, the cabal was within a State Dept of Transportation where certain employees were engaged in what we termed “reverse bid-rigging” to the tune of millions and discrimination against a bridge and highway contractor. Basically, the cabal was determining who would get the contracts before there were even bids opened.
Case settled later for a tidy 7 figure sum.