Cast shake-ups come with the territory of any long-running series but CBS's stalwart crime drama "CSI" has weathered more than a few storms over the last few years. When William Petersen left, the addition of Laurence Fishburne never fully clicked so this past year Fishburne was out and TV staple Ted Danson was in. However, just as Danson was settling into the show as D.B. Russell, it was time for original cast member Marg Helgenberger to leave after twelve seasons. Last week, we met Elisabeth Shue's Julie (Finn) Finlay as the latest addition to the cast.

What were the challenges in bringing on an actress strong enough to fill Helgenberger's void and also help Danson carry the show? How were the characters of Russell and Finn created to blend in with the long-running series and what exactly is their hush-hush history all about? What's next for other cast members like Jorja Fox (Sara) and George Eads (Nick)? Our Jim Halterman did some investigating of his own during a phone chat yesterday with Executive Producer Don McGill.

Jim Halterman: With the casting ups and downs the last few years, were you confident that Ted Danson would fit in when he joined last fall? His addition to the show really seems to work well.

Don McGill: It absolutely works and the character of Russell we came up with independent of thinking about Ted. There was a short list of actors and Ted was at the top of the list. We called him and he was actually quite happily enjoying some down time in Martha's Vineyard and I feel bad because basically we ruined all his down time. We got on the phone and pitched the idea of the D.B. Russell character, who is sort of a West Coast Sherlock Holmes...he was home-schooled, toured with his family in a band - they were folk singers - [and] he was sort of this crazy character to be the basis for a crime fighter. and Ted immediately responded and once he came on board, really, from day one, it was almost like he'd always been here. We were just so, so fortunate. Ted is the nicest guy and as an actor he's super smart, obviously very funny and really generous on set and off. We completely lucked out because he can play humor, he can also play, as he's demonstrated on 'Damages' and in his film career, drama with a dark edge. He just turned out to be the perfect fit for the show, especially for the direction of the show we wanted to go as it's evolved this year.

JH: So which came first, the character of Finn or Elisabeth Shue?

DM: Again, we had this idea for this character and, as with Ted, we had the basis of the character but with Russell so much of that character turned out to be very much Ted so he very early on started to own it. What we started out with the Russell character and where we've gone with it has really been collaboration with Ted Danson and with the writers. The same thing with Elisabeth Shue. We started with this character, this strong woman, who did have a history with the Russell character, which we thought was fun and important. One of the first things that we pitched out is since Russell is kind of an iconoclast and surprising in choices, what if the person he reached out to join the team was someone he'd fired? That would be unexpected, which is part of the Russell character, but also an interesting mystery for the rest of the season - why bring her in and what happens?

We had this idea for a character and then we talked to Elisabeth Shue and pitched it to her and she was really interested and now that she is here she brings so many qualities that we're sort of folding into the character that are a part of her. For example, Elisabeth is a serious tennis player and so we've made that a part of the Finlay character; we haven't seen it yet but we will. I think Elisabeth herself would say that she's very competitive in her nature and we wrote that into the Finlay character and she's someone who is sort of aware of her effect on men in a positive way and we've folded that into the character. There's a tomboy quality to Elisabeth and also a leading lady quality so we brought that to Finlay. And, like Ted, she's super sweet, so smart and it was the same thing, from Day One - and I'd have to say the whole cast was so excited to have both actors join - and in the beginning we had the feeling with Elisabeth that she just walked onto the set and it was a perfect match and it feels like she could've been here since the pilot.

JH: How important was it that she have chemistry with Ted? There's history with these characters but I noticed a really nice spark between them. Is this just a working relationship or is there a hint of a romantic one? Have you noticed that spark?

DM: Yes, absolutely! And we are going to reveal all but this much I can say - the Russell character is a happily married man. He married his high school sweetheart and she was the only woman for him. But naturally, a beautiful woman with whom he works and at the work place shares all his interests... that's not to say that there isn't a natural attraction but it's like 'When Harry Met Sally.' Whenever men and women are together in these situations there's always something underneath. Now whether that means they have any sexual history, I don't think we're presuming that but I do think, if anything, there's a closeness there.

The backstory between them is that they worked together at the crime lab in Seattle, which is where the Russell character was before he came to Las Vegas and 'CSI.' They worked together and there was a closeness. Russell hired her as a young CSI who was a go-getter and, in a way, he was a mentor for her, took her under his wing. It's a closeness that went so far as Russell, who usually keeps work and home separate, I think that the Finlay character was someone he brought home to dinner to meet the family so she knows his life and his kids. We reference that in the episode that comes immediately [after 'Stealing Home']. We have an episode that takes place on the WLVU campus, which is our fictional University. Russell's son Charlie (Brandon Jones) is a student there and Charlie gets in the mix in the next episode and we see Finlay and Charlie encounter each other and we get a sense that, yes, there's a lot of history there and she's an intimate to Russell and to Russell's family. But that's not to say that coming from the Finlay side that there may be a sense of a little bit of stronger feelings for Russell. Even if, perhaps, it was never something acted on, I think there is a little something under the surface.

JH: With these changes, did you also see an opportunity to expand on some of the other characters like Nick (George Eads) or Sara (Jorja Fox)? Take them in a different direction?

DM: 'CSI' has always had these really rich characters and we have such a great cast of actors that, yeah, in terms of storylines with Nick's storyline, Greg's [Eric Szmanda) storyline, Sara's storyline... and all of our characters we, where we can, we're looking for places to hint at a life outside the crime lab. We've touched on it a few times. Nick had a flirtation with a nurse in episode 14, which we still talked about in 15. We're opening things up a little bit for opportunities to lay in some character threads while still being true to the mission of 'CSI' and what has made it so successful, which is great crime stories every week.

JH: What are the rules for bringing people back? Petersen has been back, I'm sure you'll want Marg back maybe next season. Can you talk about how you do that?

DM: [Executive Producer] Carol Mendelsohn has always said the door's always open and no one every really leaves 'CSI' and I think that's absolutely true. For example, with Jorja Fox, Sara left 'CSI' for a bit and then came back and that's been super successful and great for the show. We talk with Billy Petersen all the time and, in fact, the episodes where we said goodbye for now to Marg Helgenberger's character, Billy was involved with that. He originally was going to be a part on-screen and there were just personal circumstances that didn't allow him to do it and we wish he had but there really are no rules. Whenever there's a great opportunity for Billy to return and we hope to create opportunities for Marg to return, the door's always open.

JH: Can you tease what we're going to see in tonight's episode, 'Stealing Home?'

DM: It's an episode about a stolen house and, more than that, it's an episode about a family and their dark secrets and the house itself holds the dark secrets. As we peel away the layers of the crime story, we're actually peeling away parts of the house to find out more and more dark secrets inside the walls, under the house, around the house and by the end we have not just dissected a house but we've dissected a family and all its dark secrets.

JH: In that family story, were you trying to reflect our CSI team? Finn says something in the episode about the team being a family. Or is that a coincidence?

DM: The episode before [tonight's episode], we meet Finlay in the context of a guest star on the show but also guest consultant within the story and at the end Russell offers her the job so the next episode, 'Stealing Home,' has her joining the CSI team. The idea was, yes, we have this really close-knit family of CSIs and now someone is coming to join the family and there's the natural question of why did Russell bring her on? I think the story of the fragmented family was a great engine for us to put forth the idea that just as you see a fragmented, fractured family on the other side you see a cohesive, loving family of crime fighters and crime solvers. And the idea was that Finn could only make the family stronger and better and the on-going story of what is a cohesive and effective CSI family.

"CSI" airs Wednesdays at 10:00/9:00c on CBS.