Who should I contact about my dad's apartment being unsafe?

My dad has lived in a house that has been convertd to a 2 tenate apartment. The upstairs is the neighbors home, and the basement is my dad's place. There have been many issues we have made aware to the landlord, but they have not yet been fixed. He moved into the place in 2006, and the problems have just been getting worse. There is a foul smell coming from the drain in the shower. When you pull the plug in the shower the sink gurgles, and emits a bad smell. When you go to plug in anything into the electrical outlets there is a blue arc, There is a yellowish brown run mark (like water trickling down the walls in the shower,) only this is on the bathroom walls. The washer pours out water when doing laundry unless something is shoved into the one pipe, the pantry wall is rotten, there is mold growing everywhere. Plain and simple we have given this man plenty of time. He had realators, and inspectors come in telling him that the place is not up to code, but he's yet to do anything. Who do I call to speed up the process?