"Your things would not be lost in any event," he went on calmly and coldly, "because I've been sitting here a long time waiting for you."
And a few moments later, he adds, "You are the only one"--that is, of the pawners--"who has not been so good as to pay us a visit."
The overall impression, which both Raskolnikov and the reader takes away from this conversation, is that Porfiry already knows Raskolnikov is the killer, and thus that his role is not to investigate the crime, but to serve as confessor to the criminal. He is the vessel into which the truth is supposed to be poured.
In a sense, every great literary detective is like this. The detective exists to receive the truth, and to know its implications. The possibility that this is so seems to mesmerize Raskolnikov--indeed, he keeps thinking Porfiry is winking at him, but is never entirely sure if this impression is real. The scene recasts Raskolnikov's supposed madness as a kind of spiritual dissonance, a moral imbalance. One thinks of President Bush's deer-in-the-headlights stare during his speech the other night, the gaze of a lunatic being dragged from his bunker into the light of day.