Countervaling political values of evidence?

There’s two issues dominating Northern Ireland at the moment. The Northern Bank, in the which the argument of the two governments (and every significant political interest in the two islands, bar one) will depend on the production of evidence, if they are to be proven. However, in the case of the McCartney killing, the converse may hold. The longer there is an absence of evidence, the greater the vulnerablity of Sinn Fein and the IRA to the accusation that they run their areas outside the terms of law or justice.