There's a moment, after Sherlock first begins to speak, in which Hal has the tiniest glimmer of hope. He knows from the very fact that they're photographs that they aren't of precisely the man (the vampire) he knows, when he knows him, but even Mr. Snow was human once, wasn't he? It's not something he likes to imagine, but it's possible, even probable, and the only escape in sight from that inevitable conclusion is that these belong to Sherlock instead.

The way he pales, like the bottom has drop out of his stomach, at those last few words is hard to miss.

"He's here?"