Crime Scenes for Writers: Ballistics

muzzle-1080231_640Ballistics is one of the older forensic sciences. As far back as the early/mid 1800s, bullets could be matched to a particular caliber of weapon. However, it wasn’t until 1895, after rifling was introduced, that ballistics came into its own. Improvements in microscope photography and the introduction of the electron microscope in the 1970s brought the forensics of guns into the modern era.

However, there are two problems with using ballistic evidence. The first is that some bullets fragment on impact. Forensic scientists need enough fragments to reproduce an image of the bullet. If they don’t have them, the bullet is of little help. The second is that, in order to compare a bullet from a crime scene to a bullet from a particular gun, the lab people need the gun. No gun, no comparison, though the bullet may be matched to other crime scenes through NIBIN/IBIS (National Integrated Ballistic Information Network).

Guns, when recovered, can yield significant information including biologics and fingerprints. I’m guessing that’s why so many murder weapons end up buried or tossed into deep water. 🙂

Other elements of investigation include the trajectory of the bullet, the velocity, if it can be determined, and the presence of gun powder residue, either on the suspect’s hands or near the victim’s wound (we’re already familiar with the term “stippling” from TV, which indicates the gun was in close proximity to the victim when fired.

Recovered suspected weapons are fired into a water tank. The bullet is removed from the tank and compared to any bullets or fragments found at the crime scene. Rifling marks, the lands and grooves, are individual to each gun. There may also be indicators of speed of rotation as the bullet passes through the barrel, and/or marks from the firing pin. Criminals who bench-load their own ammo probably leave tooling marks and individual elements in their gun powder as well.

I was happy to see a show this past year in which a detective explained to a gang member exactly why holding the gun sideways gangsta-style was a bad idea. The kid didn’t listen and the gun ejected the shell into his face. It brings to mind the fact that investigators can tell a lot about the gun and the position of the shooter by where the shell casings end up.

Speaking of shells, we’re also familiar with the term “policing the brass,” which indicates the shooter picked up his spent shells and took them with him. Most shooters don’t take the time, possibly leaving behind prints or other information with the casings themselves. I had some first-hand experience due to an unruly neighbor. My husband and I got a mini-lesson in trajectory and helped locate the casings. Each was picked up with care and stored in evidence. That’s why I own a revolver. (Just kidding . . . about the why, not the revolver.)

This doesn’t just refer to guns, but one thing TV routinely gets wrong is the use of plastic bags for evidence. Most evidence is collected in paper bags. Guns may be put into a paper bag or wrapped in brown paper. Paper preserves the evidence that plastic might easily destroy.

Several great sites exist for writers who want to know more about ballistics and guns in general to create accuracy in their stories. For examples, the NSSF published The Writer’s Guide to Firearms & Ammunition as a pdf download. But my favorite of all time and my go-to for questions is Lee Lofland at The Graveyard Shift. If you are at all interested in writing crime stories, his site should be your first bookmark.

Next week is trace evidence.


 

Do you find ballistics evidence an interesting part of the story or less so? If not your favorite, do you think it’s because we’re more familiar with it?

Other posts in this series:

Crime Scenes for Writers: Introduction

Crime Scenes for Writers: Reading the Scene

Crime Scenes for Writers: Fingerprints

Crime Scenes for Writers: Blood Evidence

Crime Scenes for Writers: Ballistics

Crime Scenes for Writers: Trace

Crime Scenes for Writers: DNA and  Biologics

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Crime Scenes for Writers: Blood Evidence

This type of evidence is often misrepresented on television. How many times have you seen a murder victim lying in a pool of blood on a TV show? These victims are usually in a thick, glossy, bright red liquid pool, right?

Not so much.

Pools of any depth begin to separate. Thin layers of blood tend to dry quickly and become dark brown. These TV victims would realistically be lying in dried, sticky brown stuff or in a sticky mess of separated plasma and browning goo. It may be one of the forensic elements on TV shows that irritates me most, but I’ll get off my soap box now.

Blood is a fascinating substance. It’s three to four times thicker than water. It has a metallic scent and taste. And it’s something we’ve all seen at some point. This “liquid life” also carries with it evidence of poison in many cases, our DNA, information about our health, our blood type, and sometimes our state of mind (adrenaline and cortisol). We’ve used the ABO blood group typing system since about 1930. It was, before DNA, what we used to eliminate possible suspects from crime scenes.

Beyond type and content, how blood is left at the crime scene gives great details about what occurred. For example, blood may be dripped, transferred, or splattered.

Dripped blood is passive, dropped in a round or elliptical pattern depending on whether the bleeding person is standing still, moving slowly, or moving fast. Read by a knowledgeable investigator, direction and rate of movement become clear.

Transfer happens when, say, a hand or sleeve comes in contact with blood and then touches another surface such as a wall or towel. If both parties have been injured (not uncommon in stabbings), their blood may mix before transfer.

Spatter is the sexy part of blood evidence for most people interested in forensics. Spatter comes in three types: low, medium, and high velocity.

Low velocity spatter is often “cast off,” or flung from an object used to strike or stab the victim. Imagine shaking water from your hands to get the idea.

Medium velocity spatter leaves larger patterns, such as arterial spray or blood erupting from the wound when struck.

High velocity spatter is a fine mist and generally caused by bullets.

The pattern of blood spatter, including voids in spatter that may mark the location of the perpetrator, reveals such things as the attacker’s height, left or right handedness, where they were positioned, and possibly how hard the victim was struck. It may also reveal the type of weapon (independent of the wounds), height, strength, and angle of the blows.

Blood is corrosive and really soaks into things. Even with a good scrubbing, traces will remain on most surfaces. It can be painted over, smeared with cleaners, even removed from the naked eye, but it cannot be eradicated completely unless you care to replace every element of the room including those floor joists.

To assist crime scene technicians in uncovering evidence of blood, the traditional method of luminal is used in conjunction with a black light.  These days, lasers are used in some cases and a new forensic camera will eventually replace luminal all together.

Beyond walls, carpet, and furniture, blood can end up in the smallest of nooks and crannies: behind unsealed baseboards, the undersides of lamp shades, on the ceiling across the room. In one case blood,  absorbed through carpet and subfloor(both of which were replaced), only to be discovered along the floor joist. It’s been found in sink drains and plumbing pipes, in soil and on plants, under furniture, in the tiny screws of eyeglasses, between a cleaned knife’s hilt and blade, and even inside the tiniest cracks of a cell phone.

There’s one more thing blood can accomplish. It can, in court, “prove” murder or death if enough blood is present to show that life could not be sustained.

Blood evidence, to my mind, is fantastic for writers. We can hold the tension of lack of evidence and then reveal a whole crime scene with luminal. We can provide what appear to be inconsistencies for our characters to resolve. If set in history, a brilliant detective might use the budding technique of studying blood evidence to solve a crime that is otherwise unsolvable. And the finding of the tiniest speck of blood in the oddest of places can make a case the reader thought was lost.


How often have you seen blood evidence used to great effect in a novel? What was your reaction?

Crime Scenes for Writers: Introduction

Crime Scenes for Writers: Reading the Scene

Crime Scenes for Writers: Fingerprints

Crime Scenes for Writers: Blood Evidence

Crime Scenes for Writers: Ballistics

Crime Scenes for Writers: Trace

Crime Scenes for Writers: DNA and  Biologics

Crime Scenes for Writers: Fingerprints

I’ve been aware that my finger prints are in a federal database for twenty-five years. My husband often jokes that I couldn’t get away with theft or murder because of it. If you were ever employed by an SEC controlled business such as I was, or have worked in a daycare in the last fifteen years, your prints are on file as well.

As far back as 1684, academics lectured on the subject of finger prints. In 1788, Johan Mayer declared our finger prints to be individually unique, but it wasn’t until 1892 that finger prints were used successfully in a criminal prosecution. The man who testified, Juan Vusetech, created a classification of loops, whorls, and arches still used today.

I should interject here that ears, a long-used identifier in Europe, are just as unique as finger prints. However, technology is advanced enough for the matching of foot, toe, and elbow prints as well. Scientists can also match whole or partial palm and heel prints as well, as long as there’s a print with which to compare.

There are two types of finger prints that can be recovered from a crime scene. The first, patent prints, are visible to the naked eye. The second type, called latent prints, must be developed to become visible.

The technique of dusting (using a fine brush of powder above the print, not actually on it) and then lifting a print with tape has been in use since the early 1900s. We’ve come a long way from the black powder and tape method, though. These days there are light powders for dark surfaces, fluorescent powders for textured or multi-colored surfaces (used in conjunction with a black light), and more recently, a laser technique that illuminates the salt and other compounds on the skin’s surface to reveal a clear, photographable print.

For surfaces suspected of holding prints that can’t be raised by more conventional methods, there are two more weapons in the lab’s arsenal. The first involves exposing the surface to vaporized superglue to reveal the print. The second, which is often used only when nothing else works, involves fine gold particles in a metal vacuum to “paint” the prints for visibility. Inroads and successes have also been achieved in lifting prints from skin and porous surfaces.

There are a few limitations to using fingerprints to identify a subject. Since most murders are committed by someone known to the victim, prints are useless unless it can be proven that the suspect has never been at the crime scene or come into contact with the items found there. If the suspect has, for example, often visited his now deceased neighbor, his prints are meaningless to prosecution as they could have been left at any time (unless of course they are left in the victim’s blood). This is a great opportunity for the writer to implicate or draw attention away from a suspect character. If, for example, the reader knows the suspect has been in the house, or has not, but evidence is either to the contrary OR excluded, you ratchet up your reader’s tension.

The other problem with prints is that, while they are unique, they can be quite similar. Print experts use a point system for comparison. Computers are able to match more, but the eight-point match is the baseline. Further points must be matched to eliminate similar prints. It is a time-consuming process and often completed by hand, not computer.

Society is quite aware that finger prints are easily left and easily found, leading more criminals to use gloves. While an actual print can’t be recovered from a gloved hand, size and grip are often evident as the gloves leave something behind as well. And, should the criminal foolishly leave his gloves behind, the prints can be recovered from inside the gloves or on their surface (as part of the process of putting the gloves on).

Prints have been recovered from places people don’t normally think about such as the inside of a belt buckle, a shell casing, the sticky side of duct tape (even after soaking in river water), larger jewelry pieces, paper, faucets, and the undersides of tables, chairs, and countertops. Basically, anywhere someone might rest a finger, a print might be recovered, and the technology will only improve with time.

Because prints are so commonplace and well known to most of us, I think they are often overlooked by both writers and readers, which is a shame. It’s an old method jazzed up by new technology, but still not as sexy as DNA or sensational trace evidence. Still, in the right circumstances, all a jury needs is one single print to convict.


Where is the most unlikely or unusual place you can think of that might yield a finger print?

Crime Scenes for Writers: Introduction

Crime Scenes for Writers: Reading the Scene

Crime Scenes for Writers: Fingerprints

Crime Scenes for Writers: Blood Evidence

Crime Scenes for Writers: Ballistics

Crime Scenes for Writers: Trace

Crime Scenes for Writers: DNA and  Biologics

Crime Scenes for Writers: Reading the Scene

Writers and readers should never underestimate a talented investigator’s ability to read a crime scene. On the other hand, they can only “read” what exists. I should note as well that in large departments, detectives or investigators may not arrive at the scene for several hours or even before the body is removed.

Here’s just a short list of things they might look for at the scene of a murder:

  • Signs of forced entry
  • Signs of struggle
  • Activities of the victim before the crime
  • Activities of the perpetrator both before and after the crime
  • Location, position, and state of the body
  • Missing, added, and out-of-place objects
  • Bullet trajectory
  • Blood location, trajectory, and characteristics
  • Observation of environmental conditions
  • Elements of overkill
  • Evidence of murder weapon

In addition to the scene itself, investigators gather information such as the last time the victim was seen or spoken to, the last time mail was taken in, anything seen or heard by neighbors or passersby, and the habits of the victim. This information is merged with the information at the crime scene to form a more complete picture. The two sets of information need to be compared and discrepancies reconciled.

The initial theory of what occurred may suggest looking for particular types of evidence or locations to search for fingerprints, DNA, shell casings, stray bullets, and possible trace evidence.

The activities of the perpetrator before and after the crime, such as attempts to clean up the scene, him/herself, posing the body, staging, preparing or eating food or lingering at the scene, and any signs of odd behavior all help police develop information about their suspect, both physically and psychologically.  These details are critical to any investigation and provide the framework that police hope will be fleshed out with forensics. This is also a great place to give your reader an obscure clue or a red herring.

The location of the crime and the lifestyle of the victim also give police useable information. A murder that occurs in a suburban home is quite different from one that occurs in a downtown alley in terms of what evidence is visible to the naked eye (and how much evidence must be sifted through and ruled out).

Careful observation and recording of all elements of the crime scene are so important that technology was developed to “map” the scene with a laser in order to recreate it digitally. However, smaller police departments still need to rely on dozens of photos, measurements, sketches, and written notes.

Some investigators will return to the crime scene several times (or more commonly, the photos, reconstruction, or notes). The more experienced and intuitive the investigator is, the more this is helpful. Regardless, it is one of the tenets of investigation that, when you get stuck, you once again begin at the beginning, examining the scene. ViCAP (Violent Criminal Apprehension System), though it has some issues,  is also an option for investigators if they suspect the perpetrator has committed similar crimes or they run out of leads.

It is only when there is so little obvious information at the crime scene that cases might hinge purely on what can be uncovered by forensic science. Developing a suspect is more difficult if the victim has been left somewhere other than where he or she was murdered (at a “dump site”), but it’s still possible to gain insight and clues.

Forensics may uncover leads not visible to the naked eye, but the fact remains that the impressions of the investigators at the scene remains the base component of any file. It is also vital information for behavior analysis, or profiling.

Next time, we’ll look at one of the oldest forensic techniques: Fingerprints.


Does your investigative character have special rituals or routines when entering a crime scene?

Crime Scenes for Writers: Introduction

Crime Scenes for Writers: Reading the Scene

Crime Scenes for Writers: Fingerprints

Crime Scenes for Writers: Blood Evidence

Crime Scenes for Writers: Ballistics

Crime Scenes for Writers: Trace

Crime Scenes for Writers: DNA and  Biologics

Crime Scenes for Writers: Introduction

Today’s juries are savvy. Today’s readers are as well. Writers of police procedurals, detective stores, and courtroom dramas need to know their subject. As readers become more sophisticated and enamored of shows like CSI, they expect the authors they select to provide factual information.

Devoted genre readers already know that television has its shortcomings. Though tests and lab procedures are getting faster and more accurate all the time, they are rarely instant, and always subject to the case load ahead in the line. The TV shows only make it look fast and easy.

Not all court cases include plentiful forensic evidence, particularly DNA. Other forms of evidence are just as important in determining guilt or innocence (or even the degree of guilt). This series will cover the most common types: the crime scene, finger prints, blood evidence, ballistics, trace evidence, and DNA recovery.

Just to debunk a few of the most prevalent myths before we get started:

  • Blood does not stay red or liquid for long.
  • Bodies begin to decompose immediately. They don’t stay normal-looking and “pretty” for the camera.
  • Rarely does a pathologist, criminologist (lab technician specializing in forensic testing related to crimes) or medical examiner participate in the detective work.
  • Crime scene technicians are their own department in most jurisdictions and do not work directly for the detectives or the medical examiner.
  • The position of coroner is an elected one in many communities. They aren’t always required to be a doctor.
  • Most autopsies are performed by pathologists. The ME acts as oversight and reviews both lab reports and autopsy results.
  • The Y incision you see on TV is usually inaccurate. I’ll cover that more clearly in the next series on the body of the crime.
  • While tests are getting faster and more accurate with advances in technology, most smaller communities don’t have forensics labs and must rely on state labs to handle their cases. It can take months to get test results.

These posts are intended as an overview. I am the first to admit I am no expert, but I’ve done my share of research and was fortunate enough to have conversations with police officers, a forensic dentist, and a former “lab rat” criminologist. I’ll try to provide links for more information if anyone is interested in launching your own research, and please keep in mind that procedures can vary by country. Also, should my information be out of date, I’d love corrective comments, questions, and shared information so we can all learn together and make our stories better.

Investigating crime may rely on the lab, but it always begins when your detective or officer steps onto the crime scene. Next time we’ll look at what can be determined from reading the scene itself.


As a writer and/or reader, how detailed do you like your crime scenes?

Crime Scenes for Writers: Introduction

Crime Scenes for Writers: Reading the Scene

Crime Scenes for Writers: Fingerprints

Crime Scenes for Writers: Blood Evidence

Crime Scenes for Writers: Ballistics

Crime Scenes for Writers: Trace

Crime Scenes for Writers: DNA and  Biologics