My story tonight on real-life CSI took me to the NYPD crime lab, which is a crime buff's paradise. It's located in an unmarked building in a remote section of Queens, and each floor is fascinating.
The ballistics lab may have been my favorite. They have wall after wall of seized guns -- I even got to hold an Uzi -- as well as a display of the most notorious items in the collection, including the .44 that David Berkowitz used to terrorize the city in 1977 and the gun that Mark David Chapman used to kill John Lennon.
We spent most of our time in the hair and fiber unit, where we learned that the contrast between the increasing use of DNA evidence and the popularity of other techniques made famous by the CSI shows is creating controversy.
Hair and fiber analysis is a traditional forensic science. As we all know from watching CSI, a criminalist looks at, say, two hairs under a microscope -- one found at the crime scene and one from the suspect -- and gives her subjective opinion about whether they could have come from the same person.
DNA evidence is different. Analysts breakdown the molecular structure of hair and use provable, established science to ascertain with mathematical precision whether the two hairs match.
The question now is whether courts should still allow juries to hear the results of old-fashioned, microscopic analysis, when better options, such as DNA analysis, are usually available.
While at the crime lab, we also learned about how the NYPD is trying to bring some of those old practices into the 21st century in a program called Biotracks, which uses DNA evidence to solve burglaries.
It turns out that burglars often eat and drink while they're stealing, and what they leave behind -- like a soda bottle -- can yield tell-tale clues that scientists can put to the test. For more on the subject, see my story in this week's New Yorker.
-- By Jeffrey Toobin, CNN Senior Legal Analyst