Does anyone have any clue who the shooter was from csi - nueva york season 5 finale "Pay Up"?

I believe Robert Dunbrook hired someone to shot the team because, he was involved with his son's kidnapping. Other evidence to prove my point is when he didn't want the team to help him his son. I believe he didn't want them to find detective angel's killer, and be ratted out be the paid help. One other piece of evidence is in Season 5: Episode 15: The Party's Over. Robert arranges to meet with someone. He goes to the park and finds Mac. Robert gives Mac a coffee and the paper that says the officers are back. Robert tells Mac it is tomorrow's headline. Robert then hands Mac a check for $20 million dollars for the department and tells him to read the fine print. Mac tells Robert it looks like he is going to be a problem for him.

Uhm...no idea..

    
I also believe that Robert has Dunbrook hires a killer to eliminate the team of Mac, because of the story he had with his son, but I'm not sure .. Also this might be a gang ... But I think más about Robert Dunbrook, although I made a check of money the police to carry out boxes

2boys and a girl... they just wanted to shoot somebody. they didn´t even know our fav team was in there..
guys tu really have to read the spoiler...