Girardi gave the cave a long look and listen for any signs of trouble as they found it, then looked to his partner for a moment. He put his finger to his lips as if to indicate for a moment's silence, checking his pistol to make sure it was where it needed to be for a snap-draw if it was required. This was odd, but not particularly threatening. Indeed, he wondered if their vagrant was inside, or perhaps some other witness.
It couldn't hurt to knock politely. He stepped to such a place where he could be seen from inside, if someone was of a mind to look. With a final look to his partner, he called out calmly, "Federal agents. Anybody inside? We'd like to talk." His tone was polite and friendly, as if he was just a guy someone should want to talk to. The police are your friends!
3 sux to perceive, 7?!!!?!?!? sux to persuade anybody inside to come have a friendly chat