The CSI Producer discusses the big crossover, what’s coming up in the remaining sweeps episodes of CSI and the return of a memorable nemesis. Lights spoilers inside!

November sweeps has already seen the historic first three CSI show crossover, but there’s more excitement to come, CSI: Crime Scene Investigation Producer Allen MacDonald promises. In addition to teasing the episode he’s at work on now–which brings back a familiar face–MacDonald discusses the return of Sara Sidle (Jorja Fox), the departure of Lauren Lee Smith and Nick Stokes’ (George Eads) promotion.

CSI Files: The three-show crossover scored big in the ratings last week. How did the plans for the trilogy originate?

Allen MacDonald: It all started with [Executive Producer] Carol Mendelsohn.  It’s something she’s been wanting to do for some time now.

CSI Files: Was the crossover tricky to pull off?

MacDonald: It was just a matter of scheduling on the part of all three shows.

CSI Files: How was Ray Langston (Laurence Fishburne) chosen to be the character to tie it all together?

MacDonald: Laurence and David Caruso (Horatio Caine) have worked together in features and very much wanted to work together again.  After that, it just snowballed. It was quite a kick to watch Langston interact on-screen with Horatio Caine and Mac Taylor (Gary Sinise).

CSI Files: What else can we expect from sweeps?

MacDonald: A Dustin Lee Abraham episode involving the world of professional bowling and a decapitated human head bowling ball. Intrigued?  Believe me, by the time teaser is over, you’ll be hooked.  It’s gross – but in a fun way.

CSI Files: Bringing in a new leading man after eight and a half seasons is obviously a big challenge. What do you feel was the most difficult thing about the transition from Gil Grissom (William Petersen) to Langston?

MacDonald: Just simultaneously having to do two very important things at the same time: giving Grissom the emotionally satisfying send-off he deserves while simultaneously setting up Langston, and making him a unique, compelling character in his own right, instead of trying to simply recreate Grissom.

CSI Files: Langston’s father seems to loom large in his mind. Are there plans to see him at some point?

MacDonald: Not that I know of — the character is dead and there are no plans to depict him in flashbacks.

CSI Files: Sara Sidle sure is spending a lot of time away from her new husband! Are we meant to read anything into that?

MacDonald: I think it’s always been clear Grissom and Sara would have a non-traditional approach to marriage.

CSI Files: What was behind the decision to have Sara and Grissom marry?

MacDonald: We felt it was a natural conclusion to where we left them both at the end of “One to Go” in the rainforest of Costa Rica.

CSI Files: What was behind the decision to promote Nick Stokes?

MacDonald: To recognize his huge contribution to the team and his growth as an emerging leader.  Catherine (Marg Helgenberger) needed somebody to back her up and Nick seemed like the natural choice.

CSI Files: Nick and Langston seem to be developing a friendship. Will we see more of this?

MacDonald: Absolutely.  They’re getting to know and trust each other.

CSI Files: Greg Sanders (Eric Szmanda) is expressing a little job dissatisfaction this season with regards to the assignments he’s getting. What’s behind Greg’s disgruntled attitude?

MacDonald: It’s like he said to Sara in the premiere, he still feels he’s being treated like the geeky DNA lab tech when, in fact, he’s matured into a seasoned CSI capable of handling anything thrown his way.

CSI Files: We’ve seen a bit more of Catherine in the leadership role this season. Will this continue?

MacDonald: Yes.

CSI Files: Is there any official word on the reason why Lauren Lee Smith (Riley Adams) didn’t return for the tenth season?

MacDonald: From what I understand, it was felt Riley never quite gelled with the rest of the team because she was introduced at a pivotal point in CSI’s history – two episodes after Warrick’s (Gary Dourdan) death and seven episodes before Grissom’s departure.  As a result, the character got a bit lost in the shuffle, which is not a reflection on Lauren, who is a spectacular actress and was much-loved on the set.

CSI Files: Are there any plans for another Lab Rats episode this season?

MacDonald: Yes.  It’s going to be written by Liz Vassey (Wendy Simms) and Wallace Langham (David Hodges), who are working on it with [Executive Producer] Naren Shankar right now.

CSI Files: Are you at work on a new episode now? Can you hint at what it might be about?

MacDonald: I am.  And the only hint I can provide is that it would be the completion of a CSI storyline trilogy involving Sara Sidle and a very, very smart young girl.