A look into a modern crime lab

I arranged a tour of the Tennessee Bureau of Investigation Crime Lab for my Sisters in Crime Chapter and accompanied a small group there yesterday. Our tour guide was an old friend from years ago, back in my magazine editor days. He has the title of Law Enforcement Information Coordinator, and he's a fount of knowledge on the Nashville crime scene. He has filled such diverse positions as deputy sheriff, TV news photographer, crime scene photographer, and police investigator.

The tour wasn't as thorough as I'd hoped, but it was laced with stories of humorous goings-on in law enforcement. In contrast to the tour I took a few years ago while researching The Marathon Murders, we only walked the corridors and looked in windows. I had taken the deluxe tour, going inside the labs and talking to technicians.

Everyone seemed to enjoy our visit, though, and I saw lots of notes being taken. Our first stop was outside the garage-like bays where vehicles are put for evidence retrieval. They have suction devices that can extract most anything from anywhere in a car or truck. Sometimes they literally take a vehicle apart looking for evidence of a crime.

As we passed through another corridor, Metro Nashville police officers and others were delivering and picking up evidence containers. Although Nashville is preparing to start construction on a new crime lab, it depends on the TBI for most of its sophisticated forensic work.

Serology occupies a large area, where all sorts of blood studies are made, including blood alcohol tests. We saw a machine that can take a small blood sample and duplicate it exactly for use in running various studies. In the old days, a small blood sample could be tested only once, then it was unfit for further use.

The fingerprint section featured a display showing how latent fingerprints could be retrieved. It included using superglue fuming to establish prints on a non-porous surface. The TBI stores more than a million prints in its facility and has access to another 55 million through IAFIS, the FBI's Integrated Automated Fingerprint Identification System.

The DNA lab was one that has taken on ever more importance. Our guide told of several high profile cases that have been solved there. One still making its way through the courts involved the 1975 murder of a young girl who disappeared while selling Girl Scout cookies in her neighborhood. For years police thought the killer was a older boy who lived nearby. When DNA came along, he was absolved. Last year a man convicted of raping a college student in 1975 was linked by DNA to the murder of a Vanderbilt University coed about the same time. Since all the crimes took place within weeks of each other, investigators had the man's DNA checked against semen found on the young Girl Scout and got a match.

The firearms lab is one of the largest and most active. We saw the room where serial numbers are restored on weapons, even after being filed off. It involves an acid process that eats away layers of metal, revealing the numbers. The metal is stressed all the way through with the original stamping. In another area, missing parts of a gun are replaced so it can be fired. We saw a mannequin-like torso that is dressed and shot at from various distances. The effects are compared with a victim's clothing to determine how far away the shooter was.

"If a guy says the gun went off during a struggle and the tests show it was fired from ten feet away," our guide said, "he'd better have long arms."

The Micro Analysis section was quite interesting. Using electron microscopes, they can blow up a grain of gunpowder to the size of a lemon and identify where it came from. Other bits of trace evidence can yield similar results.

Each of the different sections of the lab had a window-box display showing what went on inside. In the area that dealt with drugs, our guide pointed out the materials involved in the production of methamphetamine, the infamous "crystal meth" that has become one of our worst drug problems. We learned of a low-rent motel not far from the TBI headquarters that had to be bulldozed and buried because of its contamination by people cooking meth.

Although our tour was not as intense or close-up as my earlier visit, we got a good look at how a modern forensic lab works miracles in finding evidence to convict criminals. But we were reminded that all of this takes time. An investigator may spend days completing the study of one small piece of evidence. It isn't the instant gratification process portrayed on the CSI shows.