St. Louis ? Thirty children in seventh and eighth grades moved about the locker room and the halls of Bernard Middle School in the Mehlville school district. They were intent on solving a crime.

They were as focused as are their heroes: the cast of the CBS show “CSI.” The youngsters were investigating a murder enactment and looking for clues, taking pictures, drawing the crime scene and interviewing their teachers, who were playing suspects, witnesses and the body.

Jim Holland, the school social worker, pretended to be a corpse. In the script he had been stabbed.

The youngsters used cotton swabs to take samples of the theatrical blood.

Courtney Roland said: “I swabbed for DNA and diseases. It’s cool to be able to do things the ‘CSI’ really does when you are only 13. I am having a lot of fun.”

The youngsters have been having fun for several weeks. The St. Louis County Police Department gives the class. It lasts eight weeks and costs $15. That includes a purple T-shirt with a gold emblem that says: St. Louis County Police.

Detective Kevin Berger of the St. Louis County Police Crime Scene Unit showed the students how to take samples and fingerprints.

In a class unit enacting an accident that involved alcohol, the Mehlville Fire Department came to the scene with a pumper, an ambulance and a rescue unit. Police dogs visited the class.

Police officer Susan Doherty established the class. She is the school officer at several Mehlville schools.

“I want them to know what police officers really do: how to solve crimes, how to deal with the public,” Doherty said. “It’s not all taking bad guys to jail.”

And no one would be upset if a few students decide to become police officers someday.

Samantha Warren, 13, likes the challenge of figuring out a murder. When she watches “CSI,” she usually can solve the mystery before the secret is revealed. The classes are helping Samantha prepare for both of her might-be careers. Samantha said, “I am stuck between acting and solving homicides.”