He was trying to get rid of Jake hence by framing him and angering the gangsters until fortunately that one gal he saved earlier was able to identity him. Make for an epic thrill ride.

I imagine Denzels character getting handed a rookie and him planning the whole thing so that it worked out in his favour, with whatever parameters that would look most acceptable to the investigators. He says he was planning it the whole week (in Rogers house), but also bare in mind Denzels character is a deperate man.
I sensed at the end that he really thought he'd get away with it. He didn't care at all for Ethans character so he would put him through that to save himself.