'They say all of them have acquired their GRCs while in prison'
That is a little odd, statistically speaking, surely?
Of the set 'males who commit crimes' there is a subset 'males who have a GRC who commit crimes or have committed crimes'. But the subset 'males who have a GRC who commit crimes or have committed crimes' should contain 'males who get a GRC and then commit a crime' and 'males who commit crime and then get a GRC'.
If no males who commit crimes got a GRC first (given GRCs have been around for some time) then EITHER:
Males who get a GRC magically become good and never commit further crimes (clearly untrue becuase of the sexual assaults we are discussing here)
OR
Males in prison get GRCs at massively disproportionate rates (I wonder why)?
OR
Males who get a GRC do sometimes commit crimes, but the prison service doesn't know about this/says it hasn't happened