If the season opener of CSI is any indication"CBS gave critics screeners of the episode this week"William Petersen is going to get quite the emotional workout in his final 10 episodes as a series regular. He gives one of his strongest performances to date as he grapples with the aftermath of the climactic shooting of Warrick (Gary Dourdan) in last seasons cliffhanger shocker. The episode also brings Jorja Foxs Sara (looking softer and prettier) back into the picture, at least temporarily.

CBS Entertainment president Nina Tassler, kicking off CBSs portion of the fall-season TCA press tour on Friday morning, spent much of her session explaining the new character who will be introduced to eventually take over the team. Described by Tassler as an outsider coming into the CSI unit not immediately as the boss, hes a doctor and scientist with an interesting genetic profile that, in certain sort of medical contexts, theyve noticed that many times serial killers have that same genetic profile. Tassler says exec producers Carol Mendelsohn and Naren Shankar arent copying Showtimes Dexter here; for one thing, hes not symptomatic.

This gentleman knows this [genetic background] about himself and is sort of on this journey to discover who his true character will ultimately become. Since [ CSI] is rooted in science, they wanted him to have a quality that would really inform his curiosity. Hes not only learning what it is to be a CSI, but also a journey of self-discovery. Tassler says the new character, who she promises will be played by an actor of stature, will give the remaining ensemble a chance to show parts of their personality that the audiences perhaps havent seen ever before or at least in a while.

With so much change afoot, Tassler is calling this the DVR-proof season of CSI.

In the bigger network picture, CBS is returning to its core strengths"procedurals with a twist, and broad comedies"in its new fall lineup, after a year in which experiments in form like Viva Laughlin, Cane and Moonlight failed to survive last season. Certainly a couple of the [new] shows are more within our wheelhouse. Theres no doubt about it, says Tessler, while noting a marked departure, an evolution in the form in terms of tone, style, sensibility. The characters are a little bit more idiosyncratic, like Simon Bakers charmingly perceptive investigator in The Mentalist and Rufus Sewells intense scientific crimebuster in Eleventh Hour.

CBS, which continues to have great success with traditional sitcoms like The Big Bang Theory and Two and a Half Men, is also trying something relatively new on Mondays with the new single-camera comedy Worst Week, an adaptation of a British comedy about a hapless stooge (affable newcomer Kyle Bornheimer) who wreaks slapstick havoc whenever he tries to impress his pregnant fiances skeptical parents (including That 70s Shows hilarious Kurtwood Smith). [ Worst Week] certainly speaks to a look to the future of comedy at the network, Tassler says.

In other highlights, Tassler did nothing to endear herself to disgruntled Moonlight fans"as if such a thing were possible"when she addressed that cult vampire dramas cancellation. While saying she loved vampires, as well as witches, werewolves and warlocks, The response to Moonlight was actually more actor-centric, so I think it certainly measures our decision on the show. Right now, I dont question the choice we made. Im not getting as much mail, and most of those comments were actor-centric. Which begs the question: Are they interested in being back in business with Alex OLoughlin? Wed love to. But dont expect another Jericho-style resurrection on this front.

Other notes:

Dont look for CBS to repeat last seasons strike-induced experiment of repeating Dexter, or any other Showtime series, on their schedule.

Scrubs Sarah Chalke will make multiple appearances in How I Met Your Mother this season. ( Scrubs is expected to wrap production on its upcoming season for ABC in early September, so shell be available.) But Tassler says, Right now, I dont think shes the mother.

Shes noncommittal about the future of 70s-set summer series Swingtown, except to say shes disappointed in the ratings but very proud of the show. I love the show.

And how will the networks biggest comedy hit, Two and a Half Men, confront the issue that Angus T. Jones isnt getting any younger? Youre going to see Angus is going to be going through typical teen [stuff]. I mean, hes 14. So it opens up a whole new treasure trove of stories. Charlies got a whole host of issues that he has to deal with in terms of having a teenager in the house.
TVGuide Links:

• CSI: Crime Scene Investigation
• Two and a Half Men
• Sarah Chalke
• William Petersen
• Angus T. Jones
• How I Met Your Mother
• Dexter
• Alex O'Loughlin
• Moonlight
• Swingtown
• Worst Week