Scene of the Crime

by Anne Wingate

  Shotgun shells are changing: Shotguns are customarily used for shooting wildfowl. There have been repeated incidents of ducks and geese dying by flocks from lead poisoning when lake levels dropped and the birds, instinctively seeking the small gravel they customarily have in their crops to allow them to digest their food, consumed lead shot left on the bottom of the lake. As a result, more and more shotgun shells are being made with safer steel shot instead of lead shot. Shotgun aficionados argue at great length as to whether the steel shot is better or worse than lead shot; what is certain is that it is lighter, and therefore steel shot needs to be about two shot sizes larger to have about the same shot pattern as lead shot. University of Utah student Joel Grose researched this situation in depth for a paper and reported that an ounce of number-six steel shot will have a considerably tighter shot pattern (that is, more pellets concentrated in a smaller area) than an ounce of number-six lead shot; in order to get the same shot pattern, number-four or even number-three steel shot would have to be substituted. (The number here pertains to a formula that calculates the number of pellets per ounce. For more detailed information, you might prefer to talk with the owner of a gun shop, as s/he can answer specific questions.)

  Grose further pointed out that a shotgun, because of its smooth bore, cannot be at all accurate at over about fifty or fifty-five yards. These items of information might be useful in writing, particularly if your character is firing a shotgun using an old shell loaded with lead shot and then a new shell loaded with steel shot.

  What does caliber mean? Caliber, which is used to describe weapons other than shotguns, has to do with the nominal diameter of the barrel (hence of the ammunition) expressed in hundredths of an inch; in real life, there are some discrepancies, but this is another of those areas I would not attempt to discuss in fiction without first talking with a gunsmith. Thus, a .38 revolver has a barrel .38-inch in diameter. A .30-caliber rifle fires bullets .30-inch in diameter. Magnum used in a description of a firearm refers not to the caliber but to the firepower of the propellant used; however, normally a magnum firearm is a slightly different caliber from the closest caliber of regular firearm—thus, you have .357 magnums which can fire .38 ammunition, but don't try to fire .357 magnum ammunition in a .38 revolver; it will fit the chamber and cylinder, but the firing mechanism and the barrel aren't meant to withstand a magnum load. However, .45-caliber ammunition cannot be used in a .44 magnum firearm at all, nor, of course, can .44 magnum ammo be used in a .45-caliber firearm. In general, it is extremely dangerous to attempt to fire anything in any firearm other than the ammunition designed to fit it. Even though in some cases ammunition may appear to fit, it may actually damage the barrel and/or firing chamber irreparably or even cause an explosion.

  Some calibers of guns and ammunition, such as the 9mm, are

  measured in millimeters rather than in inches. This measurement format, however, remains relatively uncommon in American-made civilian firearms, although it is frequently encountered in European-designed weaponry and in military firearms.

  Sometimes, ammunition and the weapons that use that ammunition are described by a name that refers both to the caliber and to the year that specific type of ammunition was first used. .30-30 ammunition was first used in 1930; .30-06 (in speech, this is called thirty-ought-six) was first used in 1906. Where weapons seem to be the same caliber but the ammunition is not interchangeable, the difference usually has to do with such things as the overall length of the cartridge and/or the explosive force of the charge, as in the case of the .22 short, the .22 long, and the .22 long rifle ammunition, which in most but not all guns can be used interchangeably.

  How can you tell whether any given ammo can be used in any given firearm? If the weapon is yours and you bought it new, the manufacturer's instructions will tell you. Otherwise, ask someone knowledgeable. By the time you're into that type of question, you've reached the point where you need a good reference book exclusively about firearms, or even better, a good gunsmith who will patiently answer questions.

  The number of lands and grooves (which of course is identical, as each two lands are separated by a groove and each two grooves are separated by a land) and the direction of twist cannot possibly be addressed in this book; firearms examiners have immense reference books containing this information. Short tables for hundreds of the more common firearms appear in American Ammunition and Ballistics by Edward Matunas, which is listed in the bibliography. If it is not in your library, you can obtain a copy of it through interlibrary loan.

  More Information Sources

  Obviously, this is only the bare beginning of an outline about weapons. If you intend to get at all technical in your fiction, you would be well advised to buy several good reference books—at least one current one such as The Shooter's Bible, which appears annually, and at least one on historical firearms. Michael Newton's Armed and Dangerous: A Writer's Guide to Weapons, published by Writer's Di-

  gest Books, is especially useful, as it is designed for the writer rather than for the police officer or forensics technician.

  Firearms at the Scene

  What firearms evidence should be collected at the scene of the crime? What can be determined from what is collected?

  Obviously, if a weapon is present, it must be collected and transported as gingerly as possible in hopes of preserving fingerprints. To handle a pistol or revolver, either lift it gingerly by the grips, or slide a pen or pencil, or a piece of string or wire, through the trigger guard behind—not in front of—the trigger, and lift it with that. When lifting it by the grips, carefully avoid touching the backstrap, the strip of metal separating the grips. A shoulder weapon is best lifted only after examining the weapon carefully and determining what part of this particular weapon is least likely to retain prints, because of checkering or repeated handling in exactly the same spot. (Checkering refers to a small, checkerboard effect carved into the surface to increase grip security.)

  In real life, Be careful! Always assume that any weapon is loaded unless you personally have verified that it is not! Every year many people are killed with "unloaded" firearms! I've seen a few too many of those corpses to feel casual about the matter. In fiction, follow the needs of the plot—which may include substantial carelessness in handling and using weapons.

  In general, it is difficult to get fingerprints from firearms, because the stock (the wooden, rubber or plastic part of shoulder weapons) and the grips (the wooden, bone or plastic handles of a pistol or revolver) are either too checkered or too often handled, or both, to yield prints. Further, the metal parts are generally too well-oiled or too often handled. However, I have gotten extremely good prints from firearms, so it's always worth trying. In fiction, you can decide whether to have prints, not to have prints, or to have prints that somebody stupidly damages.

  Remember, always, that the weapon, like any other piece of evidence, should be photographed and triangulated before being moved. (This does not mean that somebody in your book can't stupidly—or deliberately—move the weapon without taking photos and measurements.)

  The weapon must be handled very carefully for several reasons.

  First, it may be still loaded, and it may have a hair trigger—that is, it may have been adjusted to discharge very easily. In fact, some shotguns will go off without anyone touching the trigger, if they are dropped or otherwise roughly handled. I worked two cases in which the victim—in one case, a twelve-year-old boy and in the other, the wife of a police sergeant—was killed with a shotgun nobody was even touching at the time. One of my cousins was seriously injured and one of my brothers narrowly escaped injury or death in two separate episodes of unintended keep-away played with a shotgun. (In both cases, the owner of the weapon was trying to get it back from a fraternal usurper.) That's something very useful in fiction, although in real life it should serve as a reminder that loaded guns should never be placed where children can get hold of them.

  Also, it is important to preserve the evident
ial value of the weapon, which might include fingerprints on the outside of the weapon as well as the rifling inside the barrel and the marks on the firing pin.

  It is essential to search for and collect any slugs that might be present at the scene, as when a slug missed or went through whoever it was aimed at. If it went through, the slug needs to be collected extremely carefully and put in a paper (not plastic) coin envelope, so that any moisture still on it can evaporate harmlessly. The lab might be able to locate microscopic fragments of cloth, bone or body tissue on it. If the slug has lodged in a wall or door frame, your detective should not try to dig it out. Instead, s/he should remove the entire section of wall or door frame and let the lab extricate the bullet. An ill-planned attempt to do the extrication may hopelessly damage the lands and grooves or other evidentiary markings.

  If, as often happens, the slug lodged inside the victim's body, the medical examiner after the autopsy should, depending on the jurisdiction, turn the slug over to the investigating officer or directly over to the lab.

  What Would Happen in Your Jurisdiction?

  How do you know what would happen in your jurisdiction?

  Ask the crime-scene technician. You may need to ask a public relations officer to introduce you to the crime-scene technician, but chances are the public relations officer himself or herself does not possess the crime-scene information you need.

  While you're about it, find out whether your jurisdiction has a coroner only, a medical examiner only, or a coroner and a medical examiner. If it has a coroner, find out what his/her qualifications are. Many coroners are no more than funeral directors. You can do a lot in fiction with an incompetent coroner.

  Things get more complicated if the shooting took place outside, or if (as sometimes happens) the slug went through a wall and exited outdoors. That's when it sometimes takes a careful search, using metal detectors if possible, to locate the slug. In that case, triangula-tion is especially important, as a line drawn from the final location of the slug through the hole in the wall can usually be extended to locate the exact spot from which the weapon was fired and, often, the height of the person who fired it as well.

  Once that has been determined, experts can, if necessary, determine from what positions the muzzle flash should have been visible and from what places the report should have been audible. Although in real life this is rarely useful, in fiction it may be possible to locate a potential witness, or impeach a lying one, based on what has been determined from these tests. (I spent the better part of two years off and on trying to get a lead on a shooting that occurred in an alley, despite the fact that I was in the alley when the killing took place and didn't know about it until it was reported.)

  Oh, you want to know more about that one? Well, it was this way. We—my husband and I—were in a mortgage company that backed onto the alley, arranging for a home loan. The back door of the mortgage company was open, and all three of us—my husband and I, as well as the agent we were talking with—heard the shot. We all got up, rushed back to the door, looked out into the alley, saw no sign whatever of any trouble, decided we had heard a backfire, and went back to the discussion in progress. I found out an hour later that the owner of a somewhat disreputable pawnshop, which was located in the alley and which sold musical instruments and repaired shoes on the side, had been shot to death—almost certainly by the shot we all heard.

  Despite a lengthy and careful crime-scene investigation and a painstaking job of investigation by detectives, no suspect was ever developed. I have a few hunches of my own, as do the others who worked on the case, but none of them ended up proving anything.

  How Far Can You Shoot?

  Be aware, both in real life and in fiction, that a weapon may be able to fire farther than the person can see. Even a little .22 long rifle bullet (despite its name, it's as often used in pistols as in rifles) may travel as far as a mile, so that a person "popping cans" on a back fence in even a sparsely populated area may kill a person inside a house two blocks away. In November 1991, while I was working on this book, two young men got themselves into serious trouble on the Wasatch Front in Utah by setting up a firing range in their above-ground basement. When they began shooting at their targets with their .22s, their bullets passed out their wall and into the wall of the adjacent house, doing considerable damage. Fortunately, no one was seriously hurt, and the firing range was quickly discontinued.

  In fiction as in real life, this carrying power means that the search for a slug—or the search for the place from which a weapon was fired, if it is known where the slug wound up—may occupy quite a large area.

  Collecting and Using the Brass

  In the case of an automatic or semiautomatic weapon, empty shells—usually referred to by police as brass—are ejected, and can be located unless the perp takes them away. Once located, the shells can be matched to the weapon (once the weapon has been located) by the firing pin mark on the shell and the ejector mark on the shell. Once again, photographing and triangulating are very important, as once the weapon is located, test firings that demonstrate how far, and in what direction, empties are ejected may—like triangulation of where the slug wound up—determine exactly where the person who fired the weapon was standing.

  The empties should be collected very carefully. Albeit rarely, it has happened that a sufficiently large fragment of fingerprint for identification has been found on an ejected shell.

  Ammo at the Scene

  When searching a crime scene in which the perp probably lived in the house or in which the perp may have grabbed a weapon that was already in the house, it is critical to locate and collect every

  source of ammunition in that house, so that shells can, if possible, be matched to the source.

  The Expert In-and Out of-the Lab

  What can be determined, and by whom, about guns and ammunition?

  • Firearms experts can usually—depending on the condition of the slug—determine what make, model and caliber of weapon fired any given slug.

  • Firearms experts can usually—again depending on the condition of the slug—determine whether a suspect weapon fired any given slug.

  • Firearms experts cannot usually determine which shotgun fired which load of shot.

  • Almost always—except in the rare instances in which a shell has been reloaded and refired several times—firearms examiners can determine which weapon fired which empty shell. This refers to handguns, rifles and shotguns.

  • Using a gunpowder residue test, forensic chemists can usually determine whether or not a given person fired a gun within the last few hours, provided the test is used quickly enough.

  Firearm and Trace Metal Residue Tests

  However, the old paraffin test, which was extremely inaccurate, has been totally discredited. Its technique of coating the hands with warm (not hot) molten paraffin, letting the paraffin harden, then stripping it off and checking it chemically for nitrates (the most common chemicals released when a gun is fired) not only gave false negatives when an insufficient quantity of gunpowder residue was present, it also gave false positives if the suspect had been working with fertilizer or even changing a baby's diaper.

  The best test is a neutron activation analysis (NAA), but this test is so expensive that it is not always used. The test is done on swabs dipped in a 5 percent solution of nitric acid and wiped over the suspect's hands in a given order with particular concentration on the palms of the hands and the webbing between the thumb and first finger, where gunpowder residue tends to collect in the creases. The NAA tests for the less-common barium and antimony contained in gunpowder. Fortunately, the same chemicals and techniques used in the field for the NAA are also used for less expensive chemical tests, so the investigator does not have to decide at once which is to be used.

  However, the better the weapon, the less powder it is likely to discharge onto the shooter's hands. A really well constructed weapon may produce a negative residue test unless an actual NAA is used, rather
than its chemical stand-in; a Saturday night special may discharge so much powder that "powder tattooing" may be visible for several days on the webbing between the forefinger and the thumb. (It may also begin to shave lead after it's been fired several times. "Shaving lead" means that the barrel is so far out of line with the cylinder that although most of the slug goes out the barrel, a thin sliver of it is propelled backwards toward the shooter's hand. This happened to me once, when I was test-firing a cheap .22 pistol. The lead shaving produced a cut and the gunpowder got in the cut. I do not recommend this for fun.)

  A trace metal test used quickly enough can almost always determine whether a particular person has held a firearm in the last twenty-four hours. This is a field test: the technician sprays a chemical from an aerosol can onto the suspect's hands and then examines the hands under black (ultraviolet) light. The hands then glow different colors according to what types, and shapes, of metals the person has handled recently. The test works because handling any metal results in the transfer of submicroscopic molecules of metal from the object to the person's hands, and the chemical is able to detect these molecules. In test situations, it has been possible to see the horse-head insignia from a Colt revolver on the hands of the person who held the revolver.

  If both trace metal and gunpowder residue tests are to be performed, the trace metal test must be done first, as the nitric acid solution removes the metal molecules on which the trace metal test depends. Also, although a lot of soap and water may on occasion remove the gunpowder residue, they usually do not remove the metal molecules the trace metal detects. This means that in fiction you can do a lot with using only one test, or with using them in the wrong order, or with letting the suspect wash his hands thoroughly before running any tests.