WATCH: 'NCIS' Reveals the Identity of the Port-to-Port Serial Killer

After terrorizing season 8 of "NCIS," the Port-to-Port Killer was finally revealed during Tuesday's episode.

Newcomer Lt. Jonas Cobb (Kerr Smith), who was brought on to help search for the Port-to-Port Killer, had his cover blown in the latest episode when Special Agent Jethro Gibbs (Mark Harmon) and his team discovered that Cobb was the murderer they've been after.

We visited the "NCIS" set in April, going behind the scenes as the cast filmed the ending to this dynamic plot line.

"You know what's interesting to me is when you get somebody that either looks or plays a good guy all the time, because it's more interesting [to see that actor] as a bad guy," said Kerr Smith, who might be best known for his clean-cut character Jack McPhee on "Dawson's Creek."

Watch the clip to see Mike Franks (Muse Watson) going head-to-head against Cobb. "NCIS" airs Tuesdays on CBS.