CRIME SCENE CHEMISTRY FOR THE ARMCHAIR SLEUTH

Prometheus Books

Contents

Acknowledgments.............................................................................................11
Apologia....................................................................................................15
Introduction: The Chemistry of Crime........................................................................17
Part I. Bare-Bones Chemistry................................................................................39
Chapter 1.  Confidence in Chemistry and Confidence in Clues: The Significance of Digits.....................47
Chapter 2.  Improbable Profiling: Finding Massive Clues.....................................................59
Chapter 3.  My Dear Watson: Elements and the Evidence They Contain..........................................71
Chapter 4.  Isolating the Witness: Screening Tests Tell.....................................................85
Chapter 5.  Fatal Attraction: Intermolecular Forces Make the Charges Stick..................................97
Chapter 6.  Volatile Situation: Mass, Gas, and Chemical Fingerprints........................................109
Chapter 7.  Too Much of a Good Thing: Establishing Concentration Levels.....................................123
Chapter 8.  Crystal-Clear Crime: Microcrystalline Identification............................................133
Part II. Felonious Interactions.............................................................................139
Chapter 9.  A Change for the Worse: When It Gets Physical...................................................145
Chapter 10. Chemistry Under the Influence: Compounding the Crime............................................157
Chapter 11. Acrimonious Adversity: Acid-Base Chemistry......................................................169
Chapter 12. Burning Passion: Runaway Redox Reactions........................................................185
Chapter 13. The Smoking Gun: Explosive Chemical Reactions...................................................195
Chapter 14. In Hot Water: Thermochemistry...................................................................205
Chapter 15. Doing Time: The Importance of Chemical Reaction Rates...........................................215
Chapter 16. The Clue Is in the GUE: Physical Equilibrium....................................................229
Chapter 17. Equal, Just as for All: Chemical Equilibrium....................................................241
Part III. Interrogation Lights..............................................................................251
Chapter 18. Enough Rope: Infrared Spectroscopy for Fiber and More...........................................257
Chapter 19. Under the Microscope: Microscopy................................................................271
Chapter 20. Sexy Science: Laser Ablation....................................................................283
Chapter 21. The Glaring Truth: Chemiluminescence and Fluorescence...........................................293
Part IV. Corpus Delicti.....................................................................................301
Chapter 22. The Prince of Forensics: Fingerprint Technology.................................................311
Chapter 23. Sticky Cases: Bodily Fluid Identification.......................................................323
Chapter 24. Unlocking the Cell: Death, Decay, and DNA.......................................................337
Chapter 25. Sniffing Out the Truth: The Future of Forensic Chemistry........................................349
Postmortem..................................................................................................357
Appendix: The Periodic Table of the Elements................................................................358
Endnotes....................................................................................................361
Bibliography................................................................................................363
Index.......................................................................................................365

Introduction

Holmes was seated at his side-table clad in his dressing-gown and working hard over a chemical investigation. A large curved retort was boiling furiously in the bluish flame of a Bunsen burner, and the distilled drops were condensing into a two-litre measure.... He dipped into this bottle or that, drawing out a few drops of each with his glass pipette, and finally brought the test-tube containing a solution over to the table. In his right hand he held a slip of litmus-paper. "You come at a crisis Watson," said he. "If this paper remains blue, all is well. If it turns red, it means a man's life." Sir Arthur Conan Doyle, Naval Treaty, ca. 1900

As chemistry books go, we believe this work to be a bit unusual in that we will be introducing each crime-scene chemistry topic with a crime-scene-setting minute mystery. As such, we thought it appropriate to commence our introduction with just such a narrative: "The Case of the Innovative Introduction."

The Case of the Innovative Introduction

Officers Vince Veteran and Rick Rookie were on routine patrol when the call came to check out a complaint of excessive noise from a party in progress. On their way to respond, they finished their conversation concerning innovations in law-enforcement equipment.

"Yep, it's amazing what the chemists are coming up with nowadays," said Officer Veteran. "All kinds of new field tests for alcohol, drugs, saliva, semen ... handheld detectors that look like penlights ... multipurpose ... real James Bond stuff-but they do the job. Pick out the bad guys and protect the vics."

Officer Rookie nodded in appreciation.

When the officers arrived at the scene, they heard loud music emanating from the house and saw revelers spilling out onto the lawn. As they pulled into the driveway they noticed a young man standing by a car. He was attempting to open the rear door while supporting a young woman who was very unsteady on her feet. The officers approached the young man and asked him if he had a problem.

"No, sir. I'm just taking her home. Some friends of mine introduced her to me at the party and, well, as you can see, we were having such a good time that she went a little overboard." He grinned sheepishly as he finally managed the door and eased his groggy passenger into the backseat. "Luckily she gave me her phone number and address before she was too far gone."

"So you think you're okay to drive?" asked Officer Veteran.

"Oh, yes, sir," the young man stated with assurance. "I don't drink at parties when I know I'm going to have to drive. I don't want to smash up my new car!" He smiled winningly at the two officers and gestured at a soda can sitting on a low brick wall that framed the driveway. He shut the back door of the car and started to open the driver's side door.

"One moment, son," said Officer Veteran. "I'd like to have a look in that backseat."

As the young man reopened the rear door, Officer Veteran pulled a flashlight from his utility belt. He turned on the light and brought it momentarily close to the girl's face. He pulled back out of the car, replaced the flashlight in his belt, and turned grimly to the young man.

"All right, son. Turn around and put your hands on the car ..."

Officer Rookie, recognizing the preliminaries of detainment, gestured toward the girl in the back seat and asked, "Too much alcohol?"

"Nope," responded his partner. "Not enough."

The Chemistry of the Case

After we have introduced each chapter's topic via vignette, as above-and before we resolve it at the chapter's end with a final "Case Closed"-we will proceed to a discussion of the pertinent chemistry in sections we have titled "The Chemistry of the Case." Here, to prepare for explanations of Officer Veteran's "James Bond stuff" and the instruments with the many flashing lights and glowing monitors we see on television crime dramas, we commence with a briefing on the chemistry and crime to come.

In parts I and II, we begin with a background in chemical principles, using examples from forensic chemistry. We can use forensic chemistry to illustrate basic chemical principles because forensic chemistry began when chemistry was basic. When we consulted a fellow chemist concerning one of the reactions we will be using for a demonstration, she commented that the chemistry seemed "rather nineteenth century," and she was right. In the 1840s, Mathiew Orfila set a precedent for forensic chemistry when he analyzed for arsenic in the body tissue of Marie LaFarge's late husband and found enough to convince a court that Madame LaFarge had served it to her husband on a plate. Although modern analysis for arsenic uses more elaborate methods than were available to the prosecutors of Marie LaFarge, there are forensic techniques in use today that employ chemistry that would have been familiar to Orfila. For instance, the presumptive field tests-tests that indicate the presence of substances such as cocaine or heroin-involve fairly elementary procedures, as we will learn in chapter 1. However, to be of evidentiary value, these presumptive tests must be backed up by confirmatory tests, which will introduce a discussion about the uncertainty in chemical analysis.

In chapter 2, we explore atomic structure and show how knowledge of atomic structure and isotopes can be key in forensic chemistry. In chapter 3, we introduce the elements, the chemical building blocks, and show how straightforward elemental analysis can sometimes provide the pivotal clue. In chapter 4, we examine compounds built from the elements as well as screening tests based on fundamental chemical principles. We will learn that these screening tests not only help determine if more expensive, time-consuming testing is needed, but they also can provide quick results. Law enforcement needs these preliminary results to focus their investigative efforts and to move swiftly to detain suspects who might otherwise flee. In chapters 5 through 8, the pieces come together as we investigate intermolecular forces and how these forces influence the different phases of substances-gas, liquid, and solid-and how knowledge of the properties of these phases is essential to the forensic chemist. For instance, in chapter 6, we will explain the functioning of the workhorse of the forensic lab: the mass spectrometer.

Part II focuses on interactions of the compounds described in part I and the laws that govern these interactions. Chapter 9 examines the difference between physical and chemical changes and how recognizing the difference can provide a missing link. In chapter 10, we will demonstrate how chemical reaction behaviors help track human social behaviors. In chapters 11 through 13, we look at acid-base, oxidation-reduction, gas-producing, and, of course, combustion reactions, and how they factor into law enforcement. In chapters 14 and 15, we discuss the role of energy in chemical reactions and how reaction rates can determine both a chemical and a criminal time line. In chapters 16 and 17, we show how physical equilibrium and chemical equilibrium help to sort out the identity of unknown materials, even in matrices as complicated as dirt and grease, various bodily wastes and discharges, plant and animal residue, or a mixture of all of the above.

In part III, we begin our consideration of the interaction of light with matter, a topic so crucial to forensic chemistry that it deserves a division unto itself. In chapter 18, we look at infrared spectroscopy as an analytical technique, and in chapter 19, we explore two important types of microscopy: light and electron. In chapter 20, the use of lasers and other specialized techniques will be considered, and in chapter 21, we examine light produced by chemical reactions, such as the fluorescence of luminol in contact with blood.

In part IV, we round up all our chemical principles, reactions, and techniques and line them up to show how biological materials are analyzed forensically: fingerprints to DNA. In our last chapter, we extend our investigation of bodily materials to bodily gases, and explain how these and other gases are related to the future of forensic chemistry-just as they resolve "The Case of the Innovative Introduction."

Case Closed

Officer Rookie peered inquiringly at his partner as the older man started a pat-down search of the detainee. Rookie now realized that the flashlight Officer Veteran had pulled from his utility belt was a PAS-Passive Alcohol Sensor-the type of device Officer Veteran had been describing to him in the patrol car. Officer Veteran recited in a monotone, "Do you have any weapons? Needles? Anything I need to know about before I check your pockets?"

"Hey!" the young man objected. "What did I do? You can't go through my pockets!" He started to remove his hands from the car roof, but Officer Veteran's no-nonsense command stopped him.

"Get your hands on the car. You are in investigative detention on suspicion of attempted kidnapping. Now is there anything in your pockets I need to know about?"

"Attempted kidnapping! That's crazy! She's drunk and I'm trying to get her home!"

Officer Veteran began methodically patting the boy's pockets and legs. "She's not drunk, son. There's no alcohol on her breath. But she is under the influence. When we test the contents of that soda," he pointed to the abandoned can sitting on the brick wall, "what are we going to find?"

A look of concern passed over the boy's face. Officer Veteran extracted a bag of pills from the boy's front jeans pocket. He looked at the pills carefully and then intoned, "You have the right to remain silent ..."

After the boy had been booked, the pills had been cataloged, and the paperwork had been completed, Officer Rookie asked Veteran to see his handheld Passive Alcohol Sensor.

"This thing can tell if there is alcohol on someone's breath from six inches away? They don't have to blow into it? Pretty impressive. Darn good flashlight, too. But what tipped you off to test the girl?"

"I got suspicious when the guy said he didn't drink at parties because he didn't want to mess up his new car, but he was willing to put an inebriated young lady in his backseat. It's pretty common knowledge what a drunk can do to the upholstery of a backseat. I figured it was worth a quick check."

"It's a good thing you found those pills in his pocket, otherwise it might have been hard to make the charges stick."

"Maybe," agreed Veteran. "But I'll bet a GC mass spec will find traces of the drug in that soda can we confiscated and cyanoacrylate fuming will produce some prints ..."

Officer Rookie nodded his approval. "Sounds like you know a lot about this stuff."

Officer Veteran shrugged. "I've made it a habit to try to keep up. I figure it's important to know how things work, when they work-and when they won't."

Officer Rookie smiled. "I wouldn't mind knowing some of what you know."

"Sure," said Veteran. "We can talk. Anytime." He reached for the squawking radio on his belt. "But right now we have to roll ..."

Public Safety-and Personal, Too The sad duty of politics is to establish justice in a sinful world. Jimmy Carter, ca. 1980

Let's review the basics.

If you don't own a pair of safety glasses, go to the hardware store and buy a pair. Wear them while doing the demonstrations in this book.

Read the safety precautions included in the demonstrations and take them to heart.

Resist the urge to get creative. Random mixtures of household chemicals can create some pretty nasty brews that can have deadly consequences. Never mix ammonia with bleach!

Be aware of sources of sparks, which can include batteries, cell phones, or electric appliances. Some of these demonstrations require batteries, so please be aware that even low-voltage, low-current batteries can generate significant amounts of heat if the leads are connected directly, even for a short period of time.

Pour waste into the toilet, not the kitchen sink or bathroom sink.

Keep amounts to a minimum. The difference between a bang and a pop is a matter of magnitude. As we will discuss, virtually any substance is harmful if there is enough of it. Water is an essential nutrient, but drowning is also a cause of death. Any pure chemical poses some sort of risk, so it must be handled with respect. If skin is exposed to pure or concentrated chemicals, rinsing the exposed area with large amounts of water is the best idea.

Know the location of the nearest working shower, fire extinguisher, and phone.

Keep everything away from children and pets.

You will be directed to use kitchen utensils in many of the demonstrations. Don't assume this means that the chemicals are nontoxic. Use plasticware and paper plates whenever possible and throw away the paper and plastic after use. Because you will probably do most of the demonstrations in the basement, garage, or bathroom, be sure to keep the chemicals well separated from toothbrushes and foodstuffs, as well as any surfaces that might come in contact with food or toothbrushes. You should cover your counters with newspaper for added protection.

Never leave a demonstration unattended unless directed to do so and then only when the materials are secured and protected from chance encounter by other people or pets.

Do not use a microwave for warming chemicals and solutions. Some solutions contain volatile components. You do not want to coat the inside of a microwave oven that will be used later for food. For warming solutions, a workable double boiler arrangement will do, as described in the following section, "Crime Lab and Crime Solutions."

Be careful that you don't expose open wounds or unprotected body parts to any of the chemicals used in the demonstrations. Do not, under any circumstances, eat, drink, or splash them in your eyes. Do not expose them to flames or sparks (unless it's part of the demonstration). Protect your clothes or wear old clothes. Protect your hands. Wear examination gloves (flexible, close-fitting gloves, usually latex) when handling chemicals and wear yardwork gloves when handling steel wool. Treat all chemicals used in these demonstrations as you would chlorine bleach, gasoline, insecticides, and other things you know to be hazardous.

Whether dealing with chemicals or criminals, a little bit of safety goes a long way.

Crime Lab and Crime Solutions

The demonstrations selected for Crime Scene Chemistry are designed around readily available household materials or materials that can be obtained from retail outlets. Nowadays, of course, these "retail outlets" include those found on the Internet, which greatly broadens the definition of "readily available." Because it makes sense to have what you need on hand (and ordering over the Internet takes time), we provide here a list of supplies. After this list, we will give directions for a setup with celery that requires time to develop and a separate section devoted to copper sulfate. Copper sulfate, an ingredient used in several of the demonstrations, has its own heading because it may be obtained from a variety of suppliers and because it warrants special precautions.

The list may look rather formidable, but it is arranged alphabetically by outlet, so that after securing the "Absolute Essentials," you have the option of waiting for your next trip to the grocery store or drugstore to collect the remaining items. Entries under the heading "Internet" will most certainly have to be ordered ahead of time. You should also scan for items marked with a double asterisk, since these may not be locally available but are possible to acquire on the Internet, too.

Absolute Essentials

Safety glasses

It is extremely important to conscientiously wear a pair of safety glasses. These glasses can be purchased at a hardware store, a scientific supply house, or an educational supplies outlet. They should be plastic and have side shields or be goggles that fit flush to the face and offer complete coverage.

Examination gloves (latex gloves) and apron

These close-fitting, flexible, disposable gloves are available in drugstores and grocery stores that sell pharmaceuticals. Some are latex and may contain a powder on the inside of the glove. Some people have a sensitivity to the latex and may have a sensitivity to the powder, so gloves made of alternative materials (hypoallergenic gloves) are also available. Find the kind that works well for you. You may also want to invest in a waterproof or water-resistant apron. Some of the materials you will be using can stain clothing. So beware! Wearing old clothes is an option, too.

(Continues...)

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Excerpted from CRIME SCENE CHEMISTRY FOR THE ARMCHAIR SLEUTH by Cathy Cobb Monty L. Fetterolf Jack Goldsmith Copyright © 2007 by Cathy Cobb, Monty L. Fetterolf, and Jack G. Goldsmith. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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