Keeping my rooms secure from my housemate?

So i've been sharing house with three people for about 8-9 months. One guy who was my friend when i moved in has turned out to be a lying sneaky bastard. He also is absolutely selfish. In the beginning he had parties several times a week, one which resulted in my room being flooded with water from the upstairs bathroom. He used to hide bills from us, and unless you could prove he had to pay something or do something he would just lie to get away. And he's in some legal battle with a previous housemate. He's recently had problems paying his rent and the landlord wants him out, but the landlord is also lazy so it hasn't happened yet (the rest of us were hoping he would get kicked out). And three weeks ago a laptop got stolen from another housemate.

SO, until i find a new place to live, i want to keep my room secure. I already installed a lock on the outside of my door and a latch on the inside. But this guy also likes to pick locks so i'm not 100% sure this would keep him out. So i was thinking a camera in my room, or if anyone knows a really good lock?

TL;DR my housemate is an asshole, i need to secure my room until i can move out. Ideas about locks or cameras? Or hey, any ideas how to efficently get back at him are welcome to.

Edit: Room not rooms. :)