Really? Exactly what would be the point? They have forensic evidence that this guy was involved and did nothing so he could do it again? Now they got this scumbag and are acting like they can't get the information of where his latest victim is? okay...I got a great idea...lets all wear orange ribbons to a football game to make ourselves feel better.
Not to be critical but I think perhaps you misunderstood what they are saying. I think when they searched his apartment after this latest event they found forensic evidence that linked to him the previous murder. They didn’t have it until now. I share your disappointment that the area has had to be exposed to this killer or killers for so many years with no arrests.
They had the DNA, they just didn't have a name and a face of who it belonged to until now.
They probably had Matthew’s DNA since 2009, derived from the seen of Harrington’s dumped body, but THEY HAD NO IDEA WHOSE DNA IT WAS UNTIL NOW.