His house is in deplorable condition. The city DON has issued citations. When she got home she found he had removed fence post to gain access to her back yard, got on her roof and has been walking on the roof and sawing by hand a large tree from her roof. Inside she has water stains on the ceiling where the roof during a storm last Friday. He was told the leave the property he was tresspassing. Can we send him a certified letter to find out if he has insurance (we doubt it). How do we deal with him without dealing personally with him?