Scene of the Crime

by Anne Wingate

  Fibers, Soil, Hair, Leaves, Pollen, Fireclay

  Any piece of small evidence that is big enough to see, no matter what it is, should be collected with tweezers and put into coin envelopes (if there is the slightest possibility that it is even slightly damp) or into small plastic bags.

  But what about the ones that are too small to see?

  This is when an evidence vacuum, a small, extremely powerful vacuum cleaner equipped with filters, is useful. The vacuum cleaner is first cleaned, even if it is always cleaned after use, just in case somebody else forgot to do it last time. Then the officer inserts the first filter, and choosing a small, easily definable section, such as the floorboard, passenger's side, front seat, s/he vacuums up everything in that area. Then that filter with its entire contents is placed in an evidence bag, the vacuum cleaner is cleaned again, the second filter is inserted, and the work continues.

  If the same area is going to be fingerprinted, it is essential to use the evidence vacuum before fingerprinting, to avoid contaminating the vacuum sweepings with fingerprint powder. Obviously, it takes something of a contortionist to vacuum an area without touching it, but ident people learn to do such things.

  Soil and Leaf Samples Outdoors

  Samples are collected from every area the perp would have contacted. Each one is packaged separately; both the evidence tag and the officer's notes should tell exactly where each sample came from. Triangulation is crucial in case someone else should have to locate the exact same spot again.

  Broken Glass

  You already know how glass is collected without damaging fingerprints. Your officer will be sure to identify, in notes and on the evidence tag, exactly where each fragment came from. The lab needs that information.

  Blood Spatters

  Blood spatters can be few and widely scattered; they can be widely dispersed over a large area. Totally accurate photography and measurements are critical. In a case in Cincinnati, a man was stabbed in the lung. Blood in the lung mixed with the air and sprayed through the exit wound, so that a fine, almost imperceptible mist of blood covered the immediate area. Detectives observed that an area of floor was not sprayed; from that they were able to ascertain the shape of the perp's jacket, and to deduce that when they found the perp's jacket, it would have blood on it. In other cases —these involving stabbing or bashing—detectives have been able to determine from the pattern of blood spattering the height and even the hand preference of the perp, and —again—to know that certain items of clothing will have blood on them.

  Not all blood is red; not all blood tracings are visible. Large amounts of blood, after being exposed to air for several hours, turn to a very glossy black and tend to dry in stacks and then crack, so that the floor will appear to be covered by irregular stacks of glossy black tile. In other situations, blood may turn pinkish, brownish or even greenish. It is very difficult to scrub all the blood up; even after the walls and floors appear immaculate to the naked eye, spraying the area with a chemical called luminol (which is available in several different trademarked packagings) will cause all areas where blood has been to fluoresce. In such a case, taking up the floorboards, tile or carpet will usually disclose puddles of blood lying on the subflooring. It may also be necessary to take apart the plumbing and look for blood traces in the sink traps.

  Smaller spatters of blood should be allowed to dry naturally, even if that involves keeping the scene sealed and guarded for several days. Then each one should be measured, rephotographed, traced in complete detail and carefully triangulated not only in location, but also in exact position within that location (is the spray coming from up or down, left or right?). Then, if possible, the surface containing the spatters should be removed to the lab.

  What can the lab do with the spatters? We'll get to all that later, in chapter nine, which tells what the lab does, and in the appendices, which provide sample lab reports.

  Let's go on, now, to firearms. They deserve a section all their

  own.

  TABLE 2_

  Processing the Crime Scene

  These pages come from the Evidence Collection Manual, published by Sirchie Finger Print Laboratories, Inc., and are used by permission. The charts have been edited for use in this publication.

  The following is a brief procedural guideline for collecting and preserving physical evidence at the scene of a crime. Any number of commercially available journals provide excellent detailed information regarding the science of evidence collection. We strongly recommend our Sirchie TB300, Evidence Collection Mission, as an outstanding source of detailed information.

  Clear the area: Clear all except essential and authorized persons from the crime-scene area. This includes all officers who are not needed for specific functions. The more people present, the more chance for damage or loss of evidence.

  Use a systematic approach: Use caution when searching for evidence. Study the whole crime-scene area first, since the relationship of different exhibit positions may be important. Systematically cover the crime scene so that nonobvious or hidden evidence is not overlooked. Speed and carelessness may lead to overlooking evidence or to the damage or destruction of important exhibits.

  Limit the number off evidence collectors: Designate one, or at most a pair, of officers to collect all evidence. This places responsibility on specific individuals. It will also tend to avoid confusion at some later date as to who recovered specific items and where they were found.*

  Photograph the evidence: Take photographs as necessary prior to moving or securing exhibits.

  Use common sense: Use knowledge, experience and intelligence in collecting evidence. Consider what significance the exhibit may have and what examinations the laboratory may conduct. With this in mind, the trained investigator will normally be able to correctly secure and preserve the exhibits.

  Keep accurate records: Prepare notes or other records as items

  *Author's note: This does not mean that only one person should search. Rather, it means that in the search team, one person should be responsible for collecting the finds.

  are collected. Record the item, its condition (if appropriate), the exact location relative to a fixed and permanent position, the date, the time, etc.

  Mark the exhibits: Place permanent and distinctive marks directly on the objects collected if this is possible without damaging the evidence.

  Mark the containers: When unable to mark the exhibit itself, such as in the case of stains, hair, paint, etc., place the evidence in a vial or small plastic or paper envelope, then seal and mark the container. Even when the exhibit itself can be marked, it is usually advisable to seal it in some kind of container and place additional identification marks on the container.

  Keep the markings brief: Initials or the name of the officer collecting the evidence is essential. In marking containers, other pertinent data can be included, such as date, location where found, case number and description of the exhibit. Do not include extraneous information or conclusions of the investigator since these might render the label inadmissible as evidence in court. Use proper containers:

  1. Plastic or cellophane envelopes are excellent for small objects that are not organic in nature.

  2. Paper envelopes are used for organic evidence (body fluids, biological evidence, etc.). Note: Air dry all evidence items before packaging.

  Seal all corners adequately if very small or powdery material is enclosed. It is preferable to place the latter in plastic envelopes. Do not use paper envelopes for fiber evidence as the paper itself may contain fibers and thus contaminate the evidence.

  3. Vials, pill boxes, capsules and like containers are frequently suitable, depending upon the exhibit and its condition.

  4. Garments and large exhibits can be placed in bags or rolled in paper.

  You have undoubtedly seen investigators on television collecting a firearm by sticking a pencil or pen down the barrel. This is, to put it very mildly, not SOP—Standard Operating Procedure. (Remember the t
erm. It's as important in police work as it is in the military.) In the first place, this procedure is unsafe; but even more important to criminal investigation, it could damage the inside of the barrel. The lands and grooves inside the barrel are the main—generally the only—way of definitely identifying which firearm fired which slug.

  What Is a Firearm?

  Let's back up a little. What do we mean when we say firearms? The more common term, of course, is gun. (Do not use gun to mean rifle in the Marine Corps. If you do, you will be required to spend several days walking around reciting to everyone you see an extremely vulgar little rhyme.)

  Categories of Firearms

  Firearms fall into two major categories, small arms, which include all the weapons normally used by civilians or police officers, and artillery, which means larger caliber weapons such as cannon and antiaircraft guns. Crimes almost never involve artillery, although a .50-caliber handgun recently invented in Utah may begin to blur the distinction. But for the time being we'll be thinking here of small arms, which include handguns and weapons normally fired from the shoulder.

  Handguns

  Revolver (although not technically a pistol, a revolver is often referred to colloquially as a pistol)

  Semiautomatic pistol (usually referred to as automatic pistol)

  Shoulder weapons

  Breechblock Rifle Bolt-Action Rifle Lever-Action Rifle Slide-Action Rifle Semiautomatic Rifle Automatic Rifle Shotgun

  A few combination weapons exist, the most common being a shotgun-rifle combination called an over-and-under, in which a rifle barrel and firing mechanism sits atop a shotgun barrel and firing mechanism. A double-barreled shotgun may be an over-and-under or a side-by-side, in which the two barrels are, as the name suggests, side by side.

  The smallest readily available handgun, designed for concealment, is the Derringer. This weapon has a very short range and little accuracy. It would be useful only in resisting or making a sneak attack. Think of it as a "lady's weapon" (as opposed to a woman's weapon, which may be anything) or a "gambler's weapon."

  Derringers in the classic style have one or two barrels, each with its own chamber and firing mechanism; another variety, the "pepperbox," has four. Derringer-like innovations include one-shot pistols disguised as fountain pens or miniflashlights; a similar item is a one-shot belt buckle fired by abdominal pressure. What it gains in sneakiness it loses in unwieldiness.

  Along the same lines are guns, knives, and stilettos disguised as belt buckles, compact cases, letter openers, keys, and just about anything else you want to name. Swords and single-shot rifles are built into umbrellas, canes and briefcases. Watching a few James Bond movies should give you more ideas.

  There are some even less common weapons, generally no longer in production, such as the "lemon-squeezer" pistol (so called because it was cocked by squeezing the grips), that I don't intend to cover here. If you're thinking of writing about anything that esoteric, chances are you're into firearms anyway.

  Ammunition

  All these weapons fire ammunition. But at this point, the terminology begins to get a little confused. For the time being, forget about shotguns. We'll get to them later. Right now we're talking about all other small arms. In the military services, normally a single round of ammunition—that is, a single item to be loaded into a firearm—is called a cartridge and the portion propelled through the air is called a bullet; but in police terminology, normally what the military calls a cartridge is a bullet and what the military calls a bullet is a slug. Decide for yourself which terminology is more appropriate for what you're writing. I'll use them interchangeably in this book.

  What is ammunition made of? Whether you want to call it a bullet or a cartridge, it has four main components:

  • The casing or shell;

  • The propellant (black powder, smokeless powder, nitrocellulose, or whatever);

  • The primer (which is hit by the firing pin, ignites with an extremely hot flame, and ignites the propellant);

  • The bullet or slug, which may be solid lead or lead jacketed with a thin layer of copper, steel or Teflon. The Teflon-coated bullets, which slip easily through bullet-proof vests and other body armor, are often referred to as cop-killers.

  How does ammunition work? The rapid ignition (which actually is not quite an explosion) produces:

  • A loud report (which can be muted to approximate a cough by a silencer on some but not all weapons);

  • A simultaneous muzzle flash (which cannot be eliminated) and forward propulsion of the bullet;

  • A mixture of hot gases and gunpowder residue that is propelled back toward the hand of the person holding the gun.

  The heat

  • Softens the bullet, forcing it to conform to the shape of the inside of the gun barrel.

  How is a shotgun shell different? A shotgun shell is slightly different; instead of a slug, it contains:

  • A primer;

  • A load of gunpowder;

  • Pellets called shot;

  • Wads, pieces of cardboard or paper packed in the shell between the primer and the powder and between the powder and the shot.

  In shotgun shells that are reloaded at home (check a large gun reference book for more about that), the wadding often is punched out of magazine pages. Many years ago in London, a police officer was murdered. At the scene, other officers found a partially burned fragment of the wadding, which came from an identifiable newspaper three years old. The search for the suspect continued for several years, but when a suspect was finally developed, officers located at his home both the pages the wadding was punched out of and additional shells loaded with wadding from those pages. This evidence proved to be the vital link to convicting the culprit. That sounds good to me. There's no reason you can't reuse it in fiction.

  Rifling

  With the exception of the shotgun, all these weapons have rifled barrels. Rifling, which was developed about five hundred years ago, consists of a series of wide spiral grooves cut into the gun-barrel. These grooves, by causing the basically cigar-shaped bullet to spiral through the air much the way a properly thrown football does, greatly improve the accuracy of flight; a smooth-bore firearm is extremely inaccurate at distances of over about eighty feet. (Now you know why you never could hit the side of a barn with a BB gun. It's smooth-bore.) The raised spaces between the grooves in the barrel are called lands. Because the heated slug conforms to and mirrors the shape of the inside of the barrel, the grooves will show up on the soft lead of the bullet (or slug) as shallow raised areas; the lands show up on the bullet as grooves cut into it. Although theoretically all the rifling on firearms manufactured in the same batch should be identical, actually, even to start with, there are microscopic differences, because the rifling equipment is worn slightly more with each barrel it rifles.

  The more the firearm is fired, the more pronounced those differences become, as the inside of the barrel, reacting to the heat and the friction of the lead rushing through it, continues to wear. This means that it is possible to identify the slug that went through any given barrel. In practice, this means that it is usually possible to tell what slug was fired from any given gun. Although barrels in some firearms are interchangeable, rarely does anybody switch them—but a recent novel had a delightful scene in which a professional killer committed a murder and then he immediately disassembled his weapon, dropped the barrel and firing pin overboard into the Pacific Ocean, attached a new barrel and firing pin, and went on about his business.

  In general, criminals don't do that. The pros might.

  In real life: This is not to say there has never been a question as to whether a particular barrel was originally on a particular gun. In the still-controversial Sacco-Vanzetti case, there is no doubt that a barrel that is now on one of the revolvers in the case is the one through which the allegedly fatal bullet was fired, and that the revolvers were in the possession of Sacco and Vanzetti when they were arrested. What does remain in question, howe
ver, is whether those particular barrels were on those particular revolvers at the time, and whether the bullet that was presented in court was the one that killed either of the men or one that was later substituted. Proper chain of custody would have prevented those questions from arising.

  The Examiner's Role

  The arrangement of lands and grooves and the twist of the spiraling vary according to the caliber, make and model of a firearm. So, faced with an undamaged or lightly damaged slug fired from an unknown weapon, the firearms examiner can generally say, with a very high degree of certainty, what make, model and caliber of gun fired it. A severely damaged slug, of course, may make such identification impossible. The slug can be severely damaged in any one or more of several ways. First, it is hot as it leaves the gun barrel. As it flies through the air simultaneously piercing the air and spinning, it continues to be heated by the friction of the air molecules. A soft lead bullet, striking anything hard, will tend to splat! and distort quite a lot; a copper- or steel-jacketed bullet may distort less from the splat effect but may shatter if it hits bone or metal. On the other hand, even a soft lead bullet that passes through only soft tissue probably will have very little distortion.

  A shotgun differs in this regard, in that, generally, the shot is not marked by the barrel. Therefore, it is not generally possible to say what load of shot came from what shotgun.

  When the gun is discharged, the firing pin hits the back of the shell either on the center or on the rim (depending on whether the weapon is center-fire or rim-fire), marking it in a way that, like the marks of the rifling, is distinctive. Therefore it is almost always possible to say what rifle, revolver, pistol or shotgun fired what cartridge or shell.

  What About Caliber and Gauge?

  You've heard firearms described as .45-caliber, 12-gauge. If you're a hunter or if you've been in the military, you probably know what those terms mean. Otherwise, you don't. So here goes.

  Gauge, which is used to measure only shotguns, has to do with the weight, in fractions of a pound, of what the shotgun would fire if it were firing solid ball ammunition instead of pellets. Thus, a 12-gauge shotgun would fire a solid ball of lead weighing 1/12 of a pound; a 10-gauge shotgun would fire a solid ball of lead weighing 1/10 of a pound. (I'd hesitate even to write about home-loading a shotgun shell this way. I'd be afraid somebody would try to do what I said and wind up blowing up the barrel, with probably fatal results.) Although theoretically this round ball of lead would exactly fit the barrel, I suspect the fit may be rather tight. The shotgun, remember, is not rifled. (It is possible to purchase rifled slugs for shotguns, but they are specially made.)