Too predictive

I believe you mean 'predictable'.

Yes, I agree with it being too predictable; the book was the same way to me. Although there was some minimal effort of the initial mention of him, I thought it was essentially screamed at us.

Also:
Well before the character mentioned it felt like the two killings were different from the other one, I didn't think it could be any more plain that there were two different things going on. I mean, they even go so far as to say that the only girl that had a chance to scratch the victim. As if we were supposed to believe that a maniac went from stab-stab-stab, axe swing-swing-swing, but then tip-toed to do the strangulation? And if the killer wanted to do it sans blood, then without Ben there, who exactly would over power the killer?
And as for Debbie having to die because she saw the Angel's face -- well, yeah, I know, he's really there to give a dying patient a hot-shot, essentially, but if he's that worried about his face, then going to a small house with potentially five people there, in the winter, he couldn't have sprung $4.50 for a ski mask?

Regardless of any of that, why exactly would we want Ben out of prison anyway?