If it had been me, I wouldn't have done it. In fact, one BIG flaw in the screenplay is that Adam never ONCE demanded proof they were alive. The finger, the tongue? These are Islamists. Those could have come from any innocent individual. I wouldn't be surprised if they just grabbed whoever was handy and did it to them. Who complies without at least INITIAL "proof of life"? I sure wouldn't. I mean, they are dragging him into crime after crime. Wouldnt he want to know they haven't already killed the rest of the family, since they obviously killed his old man?
Lynch all trolls.