I've watched Se7en so many times now and each time I find something new. I never noticed before, but Somerset consistently tries to convince Mills to leave. Almost like from murder one, Somerset knew where this was going. We catch fairly early on that Somerset takes and gives out bribes. Although they never spill who he bought it from Somerset is the only one we know for sure has been to Mills apartment. He would know where they live. Also in the car, Somerset seems to solemnly agree with John Doe's "innocent?" speech. You can really read it on his face. Finally when they are in the field John Doe remarks "he didn't know [about the baby]" and looks at Somerset as if the two had shared a secret. Could Somerset have sold Mills' address to the Press? i.e. John Doe?