Forensic Labs and Reality

by Lisa Black
Author of Blunt Impact
 
From TV you get the impression that forensic labs are vast, gleaming expanses of glass walls and expensive equipment, with mood lighting and every possible resource. I have worked in forensic labs for 17 years and the truth is not quite that glamorous. 

Forensic labs have come a long way and they’re improving constantly, yes. I’ve had two jobs in this field so far and at both places we moved to a new facility, got lots of new equipment and added personnel…but we still don’t resemble anything on CSI.

Sometimes aspects of that extremely high-tech TV lab aren’t real. In no department or agency anywhere in the United States can your average tech take a fingerprint and search it against every single person who has ever been fingerprinted in the world, including job applicants and military. Despite the fact that you’ve seen it on TV every day for the past 50 years, it isn’t true. It may be true sooner than I think, but it is not true now. 

Most databases are local. My database consists of people arrested in the city of Cape Coral, Florida, and recent arrestees in the surrounding county. I can search the databases of selected other cities (about 10) by going through some extra steps. I am embarking on a procedure to search the FBI database (insert sound of angels singing here) but I have no idea yet exactly how that will work. I have no access to job applicants or current personnel, even our own, and certainly not military. This is not backward. The technology has made amazing leaps in just the past decade or two, but it’s still not TV.

We also do not have databases with the chemical formula of every material known to man, such as perfume, wall paint or toothpaste. Companies make their living producing these items, so they’re not going to publish their formulas to any Tom, Dick or Harry who happens to ask. We do have mass spectrometers or FTIRs to analyze the chemistry of such items, but even the most underutilized lab tech is not going to have the time or resources to gather a sample of every kind of paint used in the world, and even if she did, as soon as she finished it would be time for next season’s colors to hit the market. 

Sometimes labs may not have a function or two (handwriting analysis, ballistics) because they’re not reasonable. How often do we really need to analyze wall paint? Most labs grew out of a local or state police department, and began with fingerprint and drug analyses (theft/burglary and drug offenses being the most common crimes committed). Other capabilities are added on from there. But if your town doesn’t get a lot of shootings, it doesn’t need a whole ballistics department when it can send any casings off to the state lab and get the analysis done for free. Perhaps not promptly, but the arrest will likely be made on witness testimony so the analysis can be done at leisure while the suspect cools his jets in a jail cell. 

How often would we really analyze the molecules of perfume in the atmosphere (as if they’d still be there five hours after the crime was committed)? Seriously, it might make a great ‘aha’ moment on a TV show, but try introducing that into a court of law. Me: “There was a hint of Chanel No. 5 in the air! The same perfume as the defendant is wearing right now!” Defense attorney: “So? They sell a bottle of that every thirty seconds.” Me: “Um, nothing. I just thought it was interesting.”

As for ‘hacking into’ the company’s database to find how many bottles they sold and then the store’s database to find out who they sold them to…well, I’m not a lawyer but I think Sears, for example, would be terrifically ticked off about that. Not to mention the ACLU. 

The capabilities of any lab will be a function of space, money and interest.

Space, for obvious reasons.

Money, for equally obvious reasons since new technology requires an investment for equipment, personnel and training. Sometimes this works out better than other times. It’s not always easy to estimate how much use you’ll get out of something when you’ve never had one before. We have a fancy ‘crimescope’ that can supposedly see undeveloped latent prints…I’ve never had much luck with it. But we also get daily use out of the large superglue fuming chamber. 

We purchased a very expensive photography setup with a great camera, filters and alternate light source for photographing fingerprints on a variety of backgrounds (shiny, printed, rounded, plastic) and developed with various methods (superglue, powder, fluorescent dyes), and even though my knowledge of working with filters and lights is more a process of trial and error than anything else, I’ve gotten a lot of use out of it to obtain prints I wouldn’t have otherwise.

And when I say ‘expensive’, I am not exaggerating. The FTIR I mentioned earlier cost $35,000, as I recall, and that was 15 years ago. I loved to analyze paint, synthetic fibers and adhesives on it, but, almost always, those items are still circumstantial evidence. I can prove the killer used the same brand of duct tape as was found in the suspect’s garage. But unless I can make a jigsaw match to that roll, the defense will just point out that the manufacturer made a lot of duct tape. I can say the fiber on the victim’s shirt is the same as the fibers in the suspect’s sweater, but how many of those sweaters did Timberland distribute?  In my current city where we do not have a lot of violent crime, I couldn’t reasonably ask the city for funds to buy one. Car paint can be much more definite, provided you’re lucky enough to have some chip off during the hit and run.
 
As the hair and fiber expert, a fading and almost completely lost field, I recently got a comparison microscope. (My boss had the idea of farming me out to other agencies since no one in the state does hair and fiber comparisons anymore…hasn’t really worked out but if you need a fiber compared, give me a call!) The problem was, there was only $12,000 in the budget and a decent comparison microscope starts at 40 grand. So, I’ve got a not-so-decent one.

DNA analysis is expensive, but we can get our samples tested for free by the state lab. However, the state lab limits us to five samples at a time, and those will probably take from one to three months, if not longer. We can get the city to pony up for a private lab which will get the results back to us much quicker but will charge from $600 to $1,000 per sample, depending on how fast you want it. And each case will have a minimum of three samples—victim, suspect and evidence. There’s no cheap way to get fast DNA.

Interest also comes into play. We continued doing gunshot residue tests after many agencies had dropped them, simply because our chief at the time believed in them. We have a fancy system capable of copying a computer (meant to be used for child pornography or white collar cases); however learning to use it requires a few long, pricey classes in other states, and after the guy trained on this quit to open a bar (long story), the powers that be are reluctant, understandably, to invest in anyone else. I do not argue with this, I just keep my head well down when the topic arises—you say ‘binary code,’ and my eyes glaze over.

In conclusion, you can’t assume what capabilities your local crime lab may possess or not possess until you ask them. And, though they certainly could be in play, you can’t assume that a lack in any area is the result of disregard, cronyism, backward thinking or bad money management. Most crime labs, like every other facility, try to do the best they can with what they’ve got. 
*******************************
Lisa Black spent the five happiest years of her life in a morgue. As a forensic scientist in the Cleveland coroner’s office she analyzed gunshot residue on hands and clothing, hairs, fibers, paint, glass, DNA, blood and many other forms of trace evidence, as well as crime scenes. Now she’s a certified latent print examiner and CSI for the Cape Coral Police Department. Her books have been translated into six languages. Evidence of Murder reached the NYT mass market bestsellers list. Visit her website at: www.lisa-black.com

Blunt Impact, available April 1, features forensic scientist Theresa MacLean and a series of murders surrounding a skyscraper under construction in downtown Cleveland. The first to die is young, sexy concrete worker Samantha, thrown from the 23rd floor. The only witness is her 11-year-old daughter Anna, nicknamed Ghost. Ghost will stop at nothing to find her mother’s killer, and Theresa will stop at nothing to keep Ghost safe. Kindle owners can find a bargain in Lisa's new book The Prague Project, written under the name Beth Cheylan. A death in West Virginia sends FBI agent Ellie Gardner and NYPD Counterterrorism lieutenant Michael Stewart on a chase across Europe as they track stolen nukes and lost Nazi gold, hoping to avert the deaths of millions of people.

Is Forensics Becoming a Woman's Job?

By Sandra Parshall

Here’s a startling fact: women are taking over the forensic science field.

I was aware that most of the female mystery writers I know – and I know a lot – are fascinated by forensics and don’t blanch at the gory details of death investigation, but I didn’t realize until I read a recent Washington Post Magazine article that female students are leading a boom in forensics education. According to the article, universities across the U.S. have added hundreds of new forensics training programs in the past 15 years, to fill the rapidly accelerating demand for people trained in the scientific investigation of crime.

And the majority of students in those programs are women.

As long ago as 2008, a survey of graduate and undergraduate forensics programs showed that 78 percent of students nationwide were female. The percentage is likely higher today.

In the three-year-old forensics program at George Mason University in Fairfax County, VA, 90 percent of the students are female. Why? William Whildin, who worked as a death investigator for 30 years before creating the GMU program, told the Post that “men tend to gravitate toward the gun-carrying jobs” while women enjoy the “more scholarly path.” Women students say they’re drawn to the field by their interest in science, a personal trauma, a desire to help society – or a love of mysteries.

An aptitude for science is essential for anyone who wants to become a real-life CSI. The women enrolling in forensics programs and going on to work in crime investigation are proving that males don’t have an edge when it comes to chemistry, biology, and other disciplines. Men don’t have stronger stomachs either, or tougher sensibilities.

Contrary to some studies that show women try to prevent other females from succeeding in their careers, women in forensics appear genuinely supportive of one another. The Association of Women in Forensic Science, based in Philadelphia, provides “networking opportunities for female forensic professionals as well as educational opportunities, mentoring and outreach programming for female adolescents ages 12-18 with the desire to pursue a career in forensic science.” The organization sponsors workshops, conferences, and other events and offers a wealth of information on its website.

In one of the member profiles on the AWIF site, Pamela J. McInnis, a laboratory director for the Pasadena (Texas) Police Department Crime Lab, offers a look at the life of a woman in the field. The daughter and sister of police officers, she wanted to work in law enforcement but didn’t want to carry a gun. When her father took her to see the crime lab, she was hooked, and she’s been working in forensics for 28 years. She enjoys the variety of cases – every day is different. She has the satisfaction of helping victims and society as a whole. At first, getting the respect of male cops was a problem, but after they worked with her they came to value her expertise and professionalism.

Ms. McInnis has two pieces of advice to anyone interested in a career in forensics. First, forget what you see on television. The work isn’t glamorous, and you won’t be interrogating suspects or making arrests. Second, get a solid grounding in science and develop the critical problem-solving skills you will need.     

The U.S. Bureau of Labor Statistics predicts a 19 percent growth in jobs for forensic science technicians between 2010 and 2020. All indications are that the majority of those jobs will be filled by women. Maybe it’s time crime fiction writers caught up with reality and started placing a lot more women at crime scenes and in the lab.
            

From Limbo with Love

Today's guest blogger, Jon Jefferson, is the “Jefferson” half of the crime fiction duo Jefferson Bass. Working in collaboration with Dr. Bill Bass, the forensic anthropologist who founded the Body Farm at the University of Tennessee, Jon writes the bestselling series of Body Farm novels. The latest, The Inquisitor's Key, comes out May 8. 

Jon Jefferson (left) and Dr. Bill Bass at the gate of the Body Farm. (Photo by Erik Bledsoe.)

by Jon Jefferson
 

A few years ago I complained to a friend – an old, wise friend – that I felt myself at a crossroads, unsure which direction to head. I was utterly in limbo, I told him – and I really hated the limbo. He listened, then he was quiet for a minute; finally he said, “You’re in the place of not-knowing, and you need to hang out there for awhile.”

I said, “But I want to know where I’m going; what the next point on the journey is.” He smiled and said something about trusting my intuition to guide me there, even if I didn’t know where “there” was until I arrived.

I’m reminded of this as I look back on The Inquisitor’s Key: a book whose seeds were planted in my mind in the 1990s, although I didn’t notice them sprouting out my ears until a year and a half ago.

The year was 1998. I’d recently started writing and producing television documentaries (a career for which I’d had approximately thirty seconds of training), and I’d just finishing shooting for a week in Rome and at the Vatican, for a two-hour Arts & Entertainment Special called “The Vatican Revealed.” (Several bits of trivia: That show—which A&E trotted out and rebroadcast for years, every Easter, and every time Pope John Paul II looked likely to die—is still available for purchase on Amazon; one Amazon customer has grumbled that the show is obviously the work of a brainwashed Vatican mouthpiece; another has complained that it was clearly made by someone with a deep bias against the Vatican… But I digress.) On the way home from shooting in Italy, we made a two-day detour, almost as an afterthought, to Avignon, France, a small city in Provence where a series of French popes reigned in the 1300s.

When I arrived in Avignon – a small-town boy from Protestant-prone Alabama – I was blown away. The city itself was lovely, a medieval jewel-box tucked into a loop of the Rhone River, but the most astonishing thing was the Palace of the Popes – an immense, impregnable fortress, protected by massive towers and soaring battlements. This would make a cool location for a movie, I thought vaguely. But that vague thought was as far as my thinking went … or so I thought.

 Fast-forward to the fall of 2010, when I was casting about for ideas for a crime novel I’d need to research and write in 2011. Avignon bubbled to the surface: a modern-day crime novel, set in a city that seemed to retain much of its medieval mystery and majesty. I began researching Avignon’s past, in far more detail than I had back in 1998. The more I learned, the more fascinating – and haunting – I found Avignon’s past to be. Here was a city that, seven centuries ago, was a village of a few thousand people. When a French pope was elected, and decided Rome posed too many dangers, he decided to relocate the papal court to Avignon. That move turned Avignon into Europe’s biggest boomtown… and into the continent’s crossroads of money and power. The population grew more than ten-fold, to 50,000. Twenty cardinals’ palaces were built in and around Avignon. Artists, musicians, and writers flocked to the papal court, which made that of the king of France look small and shabby by comparison. There were scandals (the writer Petrarch called Avignon “the whore of Babylon,” charging members of the papal court with orgies and incest), power-plays, and mysteries. Chief among the mysteries was the disappearance of Meister Johannes Eckhart, a prominent theologian and preacher who came to Avignon to defend himself against charges of heresy and was never seen again.

Before long I found myself writing two stories about Avignon – a 21st-century murder and a 13th-century mystery – linked by old bones and by timeless evil: the lust for power, masquerading as piety and religious fervor.

When I finished writing The Inquisitor’s Key, I grieved. The time I spent hanging out in Avignon – Avignon on the Rhone, and Avignon in my mind – was the richest, most intense period of writerly immersion I’ve ever had. I miss the place, and I especially miss the medieval characters – the mooning and self-righteous Petrarch, his beloved and unattainable Laura, the earthy painter Simone Martini, even the heretic-obsessed inquisitor, Jacques Fournier.

What’s next, now that this one’s done? I wish I knew. I’m at a crossroads, hanging out, unsure which direction to head. I’m utterly in limbo, and I really hate being in ...

Oh.

Oops.

Did I mention that I love the journey?

 

For more on Jefferson Bass, LIKE them on Facebook, read their blog, follow them on Twitter, and visit their website. Also available: a 99-cent e-story prequel to The Inquisitor’s Key entitled Madonna & Corpse.

D.P.Lyle: The CSI Effect

We are pleased to have D. P. Lyle, MD as our guest today. He's the friend of mystery writers everywhere because he helps us murder our fictional victims with poisons, bludgeon them with blunt instruments, stab them, shoot them, or just find them in their different states of decomposition. He'll tell us what the body looks like when frozen in a lake, burnt in a building, or buried in a shallow grave.

He's also the Macavity Award winning and Edgar Award nominated author of the non-fiction books, MURDER & MAYHEM, FORENSICS FOR DUMMIES, FORENSICS & FICTION, FORENSICS & FICTION 2, and HOWDUNNIT: FORENSICS as well as the Samantha Cody thrillers DEVIL’S PLAYGROUND and DOUBLE BLIND, the Dub Walker Thrillers STRESS FRACTURE and HOT LIGHTS, COLD STEEL, and the media tie-in novels ROYAL PAINS: FIRST, DO NO HARM and ROYAL PAINS: SICK RICH based on the hit TV series. His essay on Jules Verne’s THE MYSTERIOUS ISLAND appears in THRILLERS: 100 MUST READS.

He has worked with many novelists and with the writers of popular television shows such as Law & Order, CSI: Miami, Diagnosis Murder, Monk, Judging Amy, Peacemakers, Cold Case, House, Medium, Women’s Murder Club, 1-800-Missing, The Glades, and Pretty Little Liars. And here he is to tell us about the CSI Effect.

You’ve no doubt heard of the CSI Effect but what exactly is it? Does it actually exist? Both the definition and whether it is real or not are controversial with experts weighing in on both sides of the issue.

It derives from the many forensic science shows, both fictional and documentary-style, that populate/dominate the TV schedule. Many point to the CBS series CSI: Crime Scene Investigation as the beginning of the effect, which then expanded with the appearance of the “CSI clones” and shows such as Bones, NCIS, Cold Case, and Forensic Files. It’s impossible to flip on the TV without seeing some crime show and forensic science is invariably part of the story. The same goes for most mysteries and thrillers you read and virtually every real-life case you see presented on national or local news.

The CSI Effect could be defined as the impact of these shows, which reveal cool and clever forensic science techniques, on the public, criminals, law enforcement officials, juries, and courts. They have created a level of expectation that simply isn’t realistic. They portray crime labs as being fully equipped with very expensive instruments and staffed with brilliant minds that magically uncover the most esoteric evidence. They make the very rare seem almost commonplace. They suggest that all these wonderful tools are widely available and frequently employed in criminal cases. The truth is vastly different. DNA is involved in perhaps 1% of cases and it isn’t available in 20 minutes. Crime labs are severely underfunded and most have meager equipment, not the plasma screens and holographic generators seen on TV. The lab techs are indeed smart and dedicated individuals but they aren’t prescient. They can’t magically solve complex crimes by simply “seeing” the solution in a microscope or within their minds. It doesn’t work that way. At least not often.

So how does all this information---or is it misinformation?--effect the public, criminals, and the police and courts? Simply put, they teach criminals how to avoid leaving behind evidence and unrealistically raise public expectations.

Criminals watch these TV shows and then alter their behavior to avoid detection. They learn not to leave behind fingerprints and DNA, to hide from surveillance cameras, to avoid using cellphones and computers in the planning and execution of their crimes, and a host of other things. Fortunately, these shows are not always accurate and don’t cover all contingencies involved in a given criminal activity, proving the old adage that a little knowledge is a dangerous thing. The criminal thinks he has thought of everything but while he focuses on one bit of evidence he ignores others. An example would be the thief who planned a breaking and entering home robbery. He knew that shoe prints could be left in the soft dirt of the planter beneath his entry point window so he took off his shoes. He then realized he had not brought gloves, so to prevent leaving fingerprints, he removed his socks and used them as hand covers. The crime was interrupted by the home owner, an altercation with blood shed followed, and the thief left a bloody footprint on a piece of broken window glass. This proved to be his undoing.

The public, and thus jury members, comes away from these shows believing that high-tech investigations are involved in every case and if the police or prosecutors fail to make DNA or blood analysis part of the case they must have done something wrong. Defense attorneys often latch on to this and use it to undermine the police investigation. During the famous Scott Peterson case, how many times did you hear news reports and pundits talk about the lack of DNA evidence as if this made the case weak? In truth, finding Laci’s blood or DNA on Scott or his clothing would be of little help. They were married, they lived together, there were a hundred innocent reasons for Laci’s DNA to be found. Scott’s conviction stemmed from his stupidity, and the fact that he was guilty, not from high-tech forensic techniques, underlining the fact that most cases are solved by good police work and not by cool science.

Back in the 1960s and 1970s, juries wanted confessions and eyewitnesses, both of which we now know can be false and erroneous. Now, after the saturation of our psyche with forensic sciences, they expect DNA and other sophisticated evidence. This not only makes gaining a conviction more difficult but also gives prosecutors pause before filing charges in cases without such evidence.

So, it can be said that the CSI Effect alters the criminal justice system in many ways. It helps criminals avoid detection, creates unrealistic expectations in the public and in juries, and makes prosecution of some crimes problematic. But there are positive aspects in that this increased interest in forensic science has led to more people choosing this as a career and indeed the number of colleges offering forensic science curricula and degrees has mushroomed.

Thank you, Doug. See more about him at his website http://www.dplylemd.com/ and his blog: http://writersforensicsblog.wordpress.com/

The Myth of the Untraceable Poison

Doug P. Lyle, MD (Guest blogger)

One of the most common questions I get from writers is: Is there a poison that can’t be found in a corpse? The answer is No. And Yes.

Much depends on the state of the corpse when it is found. If severely decayed or completely skeletonized, the medical examiner and the forensic toxicologist have their hands tied. Mostly. There are some toxins, such as the heavy metals (mercury, lead, and arsenic are common ones), that can be found in bones and hair. But most toxins can’t be found in corpses that are severely decayed or simply bones.

In a more or less intact body, your villain can still get away with the murder by poison. That is, until your clever sleuth figures out that something is amiss and solves the crime.

The first thing your murderer must consider is how to make the poisoning look like something else. An example would be an elderly person with heart and lung disease who dies in his sleep. In this case, the person's private physician would sign the death certificate as a natural cardiac death and almost always the M.E. will accept it. Why? Because there is an old adage in medicine that says: Common things occur commonly. Most people who die in this situation do indeed die from natural causes, so searching for something more sinister would be neither logical nor practical. If the M.E. accepted the private physician’s cause of death, no autopsy would be done and no toxicological examinations would be undertaken. An overdose of morphine or digitalis or arsenic or anything else would go undetected.

Unless someone asked questions. Maybe a high-dollar inheritance or insurance policy is in play. If an inheritance, one family member could suspect another and ask questions. In the case of a large insurance policy, the insurance company would look under every stone before paying off the policy. Or your sleuth could have some reason to suspect that things are not as they seem. In any of these situations, the ME might be moved to open a file and investigate.

But if your killer is clever, he might be able to keep the M.E. completely out of the picture or at least give him an easy answer for the cause of death. If no murder is suspected, he'll take the path of least resistance, which is also the cheapest route. Remember, he must live with and justify his budget annually. If he is wasteful he'll be looking for a job. So, give him a cheap and easy out. Your sleuth will then have to battle the M.E. to get the case re-opened.

The second thing a clever poisoner can do is to use a poison that is not readily detectable and will slip through most drug screens. Toxicology testing follows a two-tiered approach. Screening tests, which are easier, faster, and cheaper, are used to identify common classes of drugs such as narcotics or amphetamines. This only tells the M.E. and toxicologist that some type of narcotic or amphetamine is present, but not which one. Determining which one requires more sophisticated, time-consuming, and expensive confirmatory testing. And if the screening tests are normal, no further testing is warranted and the M.E. would not spend the time and money to go further down that road.

Drug screens typically test for alcohol, narcotics, sedatives, marijuana, cocaine, amphetamines, and aspirin. Some screen for a few other classes. Once a member of a class is identified, then confirmatory testing will determine exactly which member of the class is present and in what amount. For example, if narcotic is found in the screen, further testing might show that the actual narcotic present is morphine. Or an amphetamine might be further analyzed and this might show that methamphetamine is the culprit.

Your poisoner could use a poison that would not be found in the typical screen. Things such as arsenic, selenium, and most plants (oleander, deadly nightshade, etc.) do not show up on the typical tox screen and when the screen came back negative, the M.E. might not go further. Why would he spend the time and money without a good reason? This is where your sleuth steps in to shake things up. But if a poison is suspected and if the funds and interest to pursue it are present, anything can be found in an intact corpse. Using gas chromatography in conjunction with either mass spectrometry (GS/MS) or infrared spectroscopy (GC/IR) will give a chemical fingerprint for any molecule. And since each molecule has its own structure and thus its own fingerprint, every compound can be distinguished from every other one.

To write a good mystery that will keep the reader guessing to the end, you must plot the nearly perfect murder. This way when your sleuth cracks the case, he or she will be a true hero. If poisoning is your killer’s chosen weapon, then use the above principles to make your plot as clever and convoluted as possible. Have your killer mask the death as natural or use some poison that is not readily detectable in screening tests and then your sleuth must be very clever to solve the case.

There are several sources for you to search out poisons and to discover how they act and how they are identified. Google, of course, and try plugging into your state poison control center. My books, Forensic for Dummies, Murder and Mayhem, and Forensics and Fiction cover a number of poisons. I also recommend Howdunnit: Book of Poisons by Serita Stevens and Anne Bannon from Writers’ Digest Books. It is a great resource for poisons of all types.

Visit the Writers Medical and Forensic Lab at http://www.dplylemd.com.

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.