Yes.
remember: tv is called PROGRAMMING, items of news are STORIES

I watched Seasons 1 to 8 long ago, but Season 9 only today.
I am still a bit confused and unsure: Who was the serial killer?
The real son of the mob boss, right?

Boyd somehow let them know where he was going to be. Yes, there was a "gentleman's agreement," since even though Barlow was a bastard and a crime boss, he had a certain codehence why he had to kill Nicholson, despite being heartbroken over it. Barlow appreciated getting the info from Boyd that Nicholson was the one who had killed his natural son (providing proof with a photo of the stamp in Nicholson's passport that showed he was in Africa at the time of Barlow's son's murder), and for delivering Nicholson cleanly to him. Since Boyd would going to have a heck of a time proving involvement by Barlow himself, and since Barlow taking out Nicholson for him was a help to Boyd and was doing the police force and the public a favor, Boyd let the murder of Nicholson go. Let a bad guy kill another really bad, hypocritical guy abusing his position of power.