What does Bob Anderson say to Harper at Erin's burial service? Why?

At Erin's burial service, Bob Anderson approaches Harper and asks him if he knows who the killer is. Harper tells him that he knows the killer's name. Bob makes Harper promise to call him when he encounters the killer. He also tells Harper that no man is immune to the temptations of the flesh, that Harper needs to make up with Drewe, and that Harper will punish himself for the role he played in Erin's death. This is Bob's way of telling Harper that he does not hold anything against him, that he knows he will do the right thing, and that he wants the opportunity to face the man who killed his daughter.