I don't believe him when he says he likes me?

He doesn't even know me that well, yet he likes me so much, and so quick. I think he just likes the idea of having a girlfriend. Every time we hang out I get hints that I shouldn't trust him... He is new to my town and came from another state where he has a shady past and had trouble with the law, I also have a deep feeling like he hurt/or killed some one. I know I should just stay away from him, but I am really attracted to him and we have some of the best times together and the same sense of humor. How can I figure this guy out? Should I tell him I'm worried about his past? How do I know if he is being honest with me?
I don't believe him when he says he likes me?
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