Whose blood is this?

Standing solemnly in the doorway, he watches and waits. The engine of the patrol car parked in the driveway across the road comes alive with a terrible clicking stutter. A cold blue light washes over him every few moments, and a red flicker illuminates the face of his neighbor in turn. Between crimson vignettes, the man notices only now that he and his neighbor look rather alike, and realizes with some shame that he does not know the name of his doppelganger.

[Approach the house across the street, and speak to your neighbor].

[Approach the car, and speak to an officer].