BS. They knew who he was because he was a known wolf.
But other people are going to be asking how they got the shooter's ID using DNA.
I'm no brainiac, but that's just not right. There is a CODIS system that could have been used, but that would require the suspect had been convicted of a felony to get his DNA in the system.
So I hope someone with chops asks the question how exactly they used his DNA to identify him.