The cops on the trio of television shows that make up the CSI franchise nearly always get it right. They go to the crime scene. They find the evidence. They apply their magic, er, science. They get their man.

But does the show itself get it right, compared to the real world? Not necessarily, according to Roger Thompson, a forensic scientist and director of the Charlotte-Mecklenburg Police Department Crime Laboratory in Charlotte, North Carolina. Here are the most glaring errors:

1. "I'm your worst nightmare: a nerd with a badge!"

"[On CSI] the [forensic] analysts are sworn law enforcement officers," Thompson says. "That's not typical of analysts. Analysts are neutral. We're supposed to be unbiased. But on CSI, they're in there interrogating suspects," says Thompson (who doesn't carry a gun).

2. 10 Cops, One Case

Another myth perpetuated by virtually all cop shows is that a team of investigators can devote all of its time to a single case. Actually, a good detective or forensic scientist has brains, good instincts, and...time management skills.

"With our chemists, for example, we probably see them working 80 to 100 to maybe 120 cases a month," Thompson says. "They have to be able to multi-task."

3. "After I processed the DNA evidence, I realized the prints matched those I lifted off a handgun last week. I fired the gun to see if I could establish a ballistics match with the slug I pulled out of decomposed corpse! The test results are in! Let's go get 'em!"

It's a good way to build drama. The bad guy is going to kill again. The cops know he's guilty, but can't...quite...prove it. The clock is ticking. But wait! New evidence! A mad scramble in the lab to get it processed, and...It's a match! Pick him up!

"We've obviously got lots of checks and balances we go through before we put that information out," Thompson says. In CSI, the same guy visits the crime scene, gathers the evidence, and processes it. "In a big department like New York," Thompson says, "there will be a group that just does firearms. That's all they do is shoot guns and look at the fragments under a microscope." Other departments have their own specialties, and investigators have to piece together information from different sources. Maybe the TV studio just can't afford to pay all those extra actors.

"Crime-solving is a complicated system that involves many people with many jobs," says Dr. Gary Telgenhoff, forensic consultant to CSI, including "homicide detectives, entomologists, CSIs, ballistics examiners, trace evidence examiners, toxicologists, lab tech, coroner's investigators, autopsy assistants, and, of course, forensic pathologists." So you may not make it as the star of CSI: Poughkeepsie, but it looks like the job prospects in real-life forensics are considerably broader.