In my humble layman's opinion, I do not think it is possible.

Burden of proof lies on the accuser, i.e. you.

Granted that what you say might be true.  They might very well have committed crimes against humanity.  But here are the questions.  First, where is the proof?  Second, can those proof positives be producible in court? Third, does US judicial system have jurisdiction over crimes committed in foreign land? 

If these two men are already here, they have already passed the US embassy's character assessment.  They have already been deemed "ok", so to speak, by the consular otherwise they would not have been given visas.

Please take this as a matter of fact.  I am not saying anything either way about what you have asserted.  All I am saying is that if you have been wronged by these two individuals, it is highly unlikely that you will get any redress here in the US.

But, what do I know?