I've only seen the first episode so far, I'm not sure the relevance of those 2 guys was known to us at that point..I assumed it would become clear later.
Jamie is the girl they found dead in the woods (I think they said her name was Jermaine or something like that, but she preferred Jamie).
The girl who was murdered was called Katy. The tramp and the other chap with the beard are friends of Katy’s father from when they were young. Katy’s father got the school cleaner pregnant and made her go to the uk for an abortion. He then married another girl who’s parents were better off after he got her pregnant.