The detectives of "CSI: NY" might finally get the one murderer that got away and that they've been chasing since season three, but first, they'll have to piece together the clues that the killer has left behind.

Shane Casey (Eddie Furlong) returns as the bad guy in the season six finale and it's up to Detectives Mac Taylor (Gary Sinise) and Stella Bonasera (Melina Kanakaredes) to track him down. "He loves to play riddles and games ... much to the dismay of Stella and the team. It's frustrating as hell," actress Kanakaredes says of the case.

Sinise adds, "He was the kind of bad guy that liked to keep a lot of clues around. He's leaving puzzles for us to try to solve. Part of his sickness is killing people and leaving clues."

So, will the detectives catch the killer? Kanakaredes is keeping mum, telling ET of the episode, "We think it's the ultimate showdown in the end."

The season six finale of "CSI: NY" airs tonight, May 26, on CBS.