To gather intel.
I’m guessing a good plan would be to capture, interrogate, shoot them while they escape, dispose of the bodies in such a way they’ll never be found.
The idea of the US detaining known murdering terrorists at a rest facility such as Gitmo, only to be released later by a sympathetic regime is just ludicrous.
I do like the way you think. But better to interrogate colonels than slick sleeves.