Kerr Smith — aka gay teen Jack McPhee — will play Lieutenant Jonas Cobb, "a confident former military man" whose "unique talents and training will play a key role in helping the team figure out the identity of the Port-to-Port Killer", the serial murderer who's been plaguing the NCIS team.
Prediction (and this isn't a spoiler, merely wild speculation): Kerr's character will turn out to be the Port-to-Port Killer. That's why you hire recognisable actors — to make them into psychopaths!
Unlike Dawson's co-stars Joshua Jackson, Michelle Williams and Katie Holmes — respectively a star of Fringe, an Oscar-nominee and a Tom Cruise wife — Kerr's been mostly out of the spotlight since the teen drama wrapped in 2003. He's popped up in series including Charmed and CSI: NY and the 2009 horror flick My Bloody Valentine.