What freaks out a CSI?

Elizabeth Becka (Guest blogger)


Our guest is the author of Trace Evidence and the just-released sequel, Unknown Means, both featuring crime scene investigator Evelyn James. When she isn’t writing thrillers, Elizabeth Becka is a real-life forensic specialist with the Cape Coral, Florida, Police Department. She previously worked as a crime scene investigator in Cleveland, the setting of her novels. Visit her web site at www.elizabethbecka.com.


Everybody’s afraid of something.

My heroine is a forensic scientist with the coroner’s office who investigates, of course, homicides. (Coroner = victims are dead.) But as part of her ‘other duties as assigned,’ she also investigates suicides, traffic deaths and industrial accidents. One such industrial accident has occurred in the salt mine which exists (I swear I am not making this up) 1800 feet below the surface of Cleveland, Ohio. Under Lake Erie, to be precise.

There’s just one problem. My heroine is claustrophobic.

So am I.

The only thing that ever scared me about working at the coroner’s office was the cooler—the large refrigerated room where the deceased, on gurneys, were stored. I hated the cooler. I couldn’t care less that it was full of dead bodies, that didn’t bother me a bit. What bothered me was that there were no windows. (I hated the cooler at my first job at an ice cream store too, and the most dangerous item there was a bag of Spanish peanuts…of course, the only dangerous thing in the coroner’s office cooler is possible exposure to TB.)

I rarely needed to go into the cooler, but occasionally it became necessary and I did it. I even shut the door behind me, because otherwise the refrigeration would flow into the hallway, wasting energy and taxpayer dollars.

There were only two things I ever refused to do at the coroner’s office: clean out the crypts, and ride the freight elevator without a light in it.

I didn’t like the freight elevator to begin with. It was one of those barbaric contraptions with the inner wall composed of grating that you had to pull shut after closing the outer door so that you could see the wall move when the elevator went up or down. At least you could have seen the wall move if you kept your eyes open, which I didn’t. It had one light bulb in the ceiling, which would occasionally burn out.

The deep freeze, a 20 x 10 room kept at minus 70 and used for storing old biological samples and bodies who weren’t going anywhere soon, had two light bulbs. The rear one had burnt out years before and had not been replaced, since the maintenance staff did not want to spend any more time in there than the rest of us, and the front one would burn out regularly too. I would go into the deep freeze armed with just a flashlight. But the perfectly empty freight elevator, no.

Please don’t point out that not having a light bulb scarcely made a difference if I kept my eyes closed anyway. It did, and you know it.

This isn’t quite as wimpy as it sounds, since most staff would consider saying no to my boss far more perilous than a silly dark freight elevator, but even she knew that you could only yank a dog’s chain so many times before it turns and bites, and did not push me.

The other thing I refused to do had nothing to do with claustrophobia. It was to clean out the old crypts (the small door and sliding tray system seen on TV, long since discontinued and used only for storage by the time I arrived there). That was out of the question because I had been traumatized about such crypts when I was a child, from the mere preview of a horror movie that made much use of surprises behind those doors. It appeared to be an utterly terrifying movie, at least to a small child, but in reality it must have been truly lousy since it doesn’t even show up in the Internet Movie Database. Doesn’t matter. The damage had been done. I would help clean out the crypts. Just not by myself.

The point is, a vital part of any suspense tale is facing something frightening, and much more so when it’s something the character finds personally frightening.

So readers are enjoying the subplot about the salt mine. It’s an interesting piece of industrial engineering, and it’s an odd role reversal: We’re used to seeing Evelyn walk up to a decomposed body without batting an eye while everyone around her is freaking out. Now Evelyn is, inwardly, freaking out, but to everyone else it’s just another day at work. 1800 feet down with a single elevator for egress? Sure, what’s odd about that? We’re actually under the lake? Yes, but there’s 1700 feet of stone between us and the water. There, that should make you feel better.

Sure.

Everyone’s afraid of something.

Shattered: Forensic Glass Analysis

Elizabeth Becka (Guest Blogger)

Elizabeth Becka is a CSI and latent print examiner for the Cape Coral Police Department, and the author of Trace Evidence. Her next book, Unknown Means, will be published by Hyperion in February 2008 and deals with a series of apparently impossible murders.

Cops get used to seeing a lot of glass. The term "smash and grab" is still used, and quite literally—most burglars aren't sophisticated enough to pick a deadbolt, when a nice handy brick through the window will do just as well. Then there's the automobile glass, broken in accidents, shattered by gunshots, or just caved in with a baseball bat by someone who decided he doesn't like you.

There are essentially two ways to analyze glass—by the patttern of breakage, or by the composition of the glass itself.

In the case of bullet holes or small punctures in glass, cracks will form around the hole. Radial cracks will radiate outward from the hole, like petals from a flower. Another set of cracks will develop as a series of concentric circles, like ripples. In either case, cracks will end at existing cracks. So if a radial crack from hole A ends in a radial crack from hole B, you know that hole B appeared first. This is absurdly easy to do and quite accurate.

If you take a piece of glass from along the line of a radial crack, the edge will show a series of wavy lines, extending straight from one side of the glass to swoosh along the inside of the other edge, forming a sort of loose L shape. These are called conchoidal fractures. The edge of the glass where the lines are straight (perpendicular) is not the side of the glass that the force came from. This is the forensic scientist's little R rule—radial cracks make right angles to the rear. In a concentric crack, it's the opposite—the chonchoidal fractures DO make a right angle to the side the force came from. This can be vitally important in determining if something was a shoot-out or a shoot-in.

Bullet holes through thick glass will also form a crater, with (as is usually the case in bodies) the larger hole on the side that the bullet exited, and the smaller hole on the side it entered. Higher-velocity bullets will leave a very neat hole. A gun held close to the pane of glass (again, like a human body) will completely shatter it, because the hot gases from the muzzle of the gun escape rapidly and with great pressure. A pane of glass broken with a large stone will look the same.

If you're standing inside and you break a pane of glass, most of the glass will land outside—but some will fly backwards towards you, landing inside the house and depositing tiny shards on your sleeves and clothing.

To analyze the composition of the glass itself, characteristics such as density and color have traditionally been studied. Float glass is created by floating molten glass on molten tin; as a result, one side of the glass will fluoresce. Whether glass is tempered can be determined with a polarizing microscope. I laughed when I saw people on the TV show CSI compare the densities of two pieces of glass by using two test tubes filled with a combination of chemicals to create a density gradient, because this is an extremely old-fashioned technique. It's still quite valid, but very rarely used for the simple reason that glass, these days, is all pretty much the same.

Up one notch from using a density gradient is determining the refractive index of glass by using a microscope and a hot stage. An attachment warms the slide with the piece of glass and a liquid; when the liquid reaches a certain temperature, it and the glass will have the identical refractive index and the glass will seem to disappear. This is a technique guaranteed to ruin your eyesight. After staring at a faint image under a colored filter for so long that you no longer trust your own eyes, well…I could never do it. Most modern labs will have a wonderful machine called a GRIM II which will do this automatically. However—the same qualifications apply. Glass is usually too similar, and while this technique can tell you with certainty if two pieces of glass are different, it cannot be so sure that they are the same.

That takes you to the next stage, the current state of the art in glass analysis -- ICP. This stands for Inductively Coupled Plasma, and it is a large, deceptively simple looking, and very expensive piece of machinery. Very few labs will have equipment like this unless some administrator got liberal with the funding, but your detective could always send the sample out to a larger, more well-equipped lab, which would most likely welcome the submission to justify their expenditure. The ICP can reportedly detail the composition of glass, down to trace elements.

The only other thing I can tell you about glass, from personal experience since I'm always wandering around where hasty burglars have been at work, is that it tends to stick to rubber-soled shoes. A lot.

Visit the author's web site at www.elizabethbecka.com.