Emotional hook keeps viewers wanting more, says writer, as show hits 14th season.

So what makes a successful TV show? For screenwriter Carol Mendelsohn, the most important thing is an "emotional hook" that keeps curious viewers coming back.

In her case, they have been coming back for 14 years to the popular CSI TV crime series, which has even survived the departure of its lead actor in its ninth season.

"All writers feel your project is like a child in a sense and you feel proud," said the 61-year-old, who is also the show's executive producer.

That CSI: Crime Scene Investigation has lasted 14 seasons is "such an accomplishment, but everybody that works in television knows it's not one person, not one department".


Seen by 63 million viewers around the world and deemed the most watched show on the planet six times, Mendelsohn says CSI's success is based in part on the fact that it brings closure to victims' families. "Because if there is a victim, there is always somebody who loved that victim," said the former Chicago lawyer who made a name for herself in the 1990s with her work on the drama series Melrose Place.

She also links the show's mass following to the fact that viewers are keen to learn new things.

"People want to learn stuff, to know things," she says. "And you can't watch an episode of CSI without learning about something.

"Whether you're learning about science or you're learning that there are people that dress up like stuffed animals and that's the only way they can interact with each other and have sex," she added in a nod to a famous episode based on a real case.

But keeping things interesting all this time hasn't been easy and is a team effort.

"These shows are really hard to write because there's science, crime and real logic, plus, people don't believe it, but there is character," she says. There, writers and forensic experts who advise them share ideas and work on multiple screens where everyone can see what their counterparts are coming up with.

"I like to work collaboratively. You never take away from someone's creativity but it always helps someone to have other ideas," Mendelsohn says.

That team used to be led by Gil Grissom, played by William Petersen, who left in 2008 to pursue other projects.

The anchor is now D.B. Russell's "family man" character, portrayed by Ted Danson.

CSI, which is set in Las Vegas, and has spawned two spinoffs set in Miami and New York, was criticised for swift DNA results, but technology is catching up with the show.

- AP