I'm actually under the impression that it was the guy Claire is dating. The reason I say this, is because of that little tidbit Parkman's partner said about the culprit "flying away". That would be a feasible argument for his involvement, because there was no body other than Kaito's at the scene, and it could explain why the culprit so openly threw himself at Kaito.
As a character, he is really shady. I'm thinking he's working for the guy that turns things into gold. He approached Claire when she first got to the school, and blatantly stalked her until he found out she had a power. He's been throwing out information to incriminate Noah, and they are leading us to believe that he is going to be the cause of Noah's death.