I could definitely see the CIA may be working with a supernatural agency to try and hunt down the brothers but every last attempt had ended up with very dead hunters in the wake of where the vampires hunt.

I could even see the brothers pitying the team merely at the idea of going after them but still giving them a horrifying battle to behold indeed. Often these two vampires stay in random run-down places places that people don't often look or out in the woods. 

Could see the CIA underestimating their target and often everyone is dead by the end of their missions only a few survived but ran off and never to be seen again. Though the vampires are not cruel doesn't mean they are not lethal and dangerous when put on target.

[@Birdboy]