“CSI: Crime Scene Investigation” has decided to go personal this season, its fifth on CBS. But that’s proving to be a mistake.
   The show’s cool gadgets, hip soundtrack and penchant for gore grab all the attention. But success for “CSI” has always been rooted in the same basic formula that all great detective series follow. In a word, predictability.
   A good detective series—be it “Columbo,” “The Rockford Files,” “Monk” or “CSI”—establishes a certain pattern and rhythm and follows it week after week. Not only that, a good detective series understands that pattern and rhythm is precisely what the audience is looking for when it tunes in week after week.
   In the case of “CSI,” that pattern also adheres to a simple rule: The investigation matters, not the investigators. That’s the essence of the show. Gil Grissom (William Petersen) and the other crime-solvers all have lives outside of the lab, but their personal stories are never more important than the procession of clues that eventually lead to the solving of the crime.
   This season “CSI” has broken that rule, taking the focus away from the investigation in an apparent effort to humanize the characters. Early episodes especially focused on the personal problems of investigator Catherine Willows (Marg Helgenberger), including her inability to deal with a rebellious 10-year-old daughter.
    The Oct. 14 episode was especially over the top, culminating in a sequence of  shark-jumping proportions that saw Helgenberger’s character dragging her young daughter into the morgue, showing her a corpse, and warning her, “This is what will happen to you if you don’t do what I say.”
   The sequence didn't work as television, and the shift to such personal back stories is not going to work. If "CSI" keeps going in this direction, we'll see viewers turn away. 
  Ratings last week were off 10 percent, one week after the morgue scene. And while much of that was because of game seven of the National League Championship Series, against which “CSI” competed directly in some parts of the country, some surely was a result of viewer dismay. 
   “CSI” is certainly not wrong to experiment. Most long-running detective series usually add a wrinkle or two in hopes of keeping the series fresh. The trick is doing it in such a way that the show remains true to form.
   “The Rockford Files” essentially reinvented itself in its third season (1976-1977). That was the year a young David Chase joined Stephen J. Cannell and Juanita Bartlett as one of the show’s three principal writers.
   Chase brought new ideas and a new perspective to “Rockford.” Though the series continued to tell private eye stories, it also began using the Rockford character as a vehicle to address politics and social issues. In this case, the shift in worked because (a) the writing was believable, (b) the social commentary never got in the way of whatever Rockford was investigating that week, and (c) the show remained true itself. “Rockford” was still a series about a detective who solved mysteries. The show continued for another four seasons, winning five Emmys along the way.
   “Columbo” added an element of danger during its seventh season (1977-1978). The seemingly bumbling lieutenant had become such a formidable threat that the murder suspects would occasionally try to kill him to keep him from cracking the case.
   This new wrinkle worked because it was executed with subtlety, allowing Columbo to escape from danger while staying completely in character. Instead of whipping out a gun or throwing a punch, he simply used his head. The device became a permanent part of the formula for the original “Columbo,” and it was also used to great effect when Peter Falk revived the series for ABC in the 1990s.
   This sort of subtlety was entirely missing from Helgenberger's morgue scene with her on-screen daughter. Helgenberger may have had her moment as an actress, but the moment was still incredulous. No rational parent would go to such extremes, no matter how bratty her kid happens to be. 
   Even the coroner (played by Robert David Hall) was shocked at Catherine’s cruelty. More to the point, it was a scene that went completely against the grain of the show, not to mention Catherine’s ordinarily level-headed nature. “CSI” is a detective series, not a soap opera. If the show’s audience wanted melodrama, they could watch reruns of Helgenberger in “Ryan’s Hope” on SoapNet.
   Perhaps in the short term, CBS and executive producer Jerry Bruckheimer would be relieved if the show's numbers were to bounce back up--it was down nearly a full rating point the following week--and they could comfort themselves that they lost audience to an exciting playoff game.
   But longer term, they and the show would gain far more if ratings continued to lag, evidence that viewers were turning away. Then they'd have every reason to examine this new direction, and the time to fix the show before more viewers drifted off.