Monthly Archives: December 2011
Ear Prints At The Crime Scene?
Human Ear
Do you want to add a little used and controversial piece of evidence to your next book scene? Consider an ear print! An ear print is just like it sounds…a two dimensional impression of residue created when a human ear is pressed against a surface. Ear print evidence has been used since the early 20th Century but it has yet to gain a lot of recognition in some countries including the United States. Ear Print evidence seems to be more frequently used in Europe and perhaps other countries as well (although I’m not sure how prevalent it is in advanced countries like Australia). Here in the United States the use has been sporadic at best even though it has been admitted into evidence in several states for over a half-century.
One reason it remains controversial is that there just hasn’t been a lot of research conducted as compared to other areas of personal identification like fingerprinting or DNA. One of the most comprehensive American texts on the subject is The Iannarelli System of Ear Identification published in 1964. Earlier texts exist dating back to the early 20th Century but these are few and far between. Some believe that the structure of the external human ear (approximately 13 possible features used in a comparison) is unique and the basic anthropometric (biological measurements) values remain unchanged despite the fact that certain portions of the ear, most notably the lobe, continue to grow until death.
Ear prints are seldom found at crime scenes. In fifteen years and thousands of scenes I’ve only found two and I never had a suspect to compare them to even if I wanted to. In one scene I found a print on the door to a safe. In the other case it was on an outside window. I wasn’t looking for them and developed them using black fingerprint powder while looking for fingerprints. In fact, since the impressions are created by the residue on the skin most fingerprint techniques could be useful for developing an impression. One concern I have as a scientist is that of distortion. Ear prints are made by pressing the ear to a surface. This pressure can be slight, great, or anywhere in between. Without getting too technical there is some concern about how accurate the impression “shape” under pressure is to test impressions used in a comparison. Bottom line, I think there is still more research to be done (of course, I’ve never studied these issues in depth).
As for your novel, I think ear prints could be quite interesting. CSI’s don’t encounter them often so they may not even recognize one when they find it. The crucial part is placing one in a believable spot. Most likely they would be found in a place where the suspect pressed their ear to listen. This could be a door, wall, window, or even someone’s chest (listening for a heart beat). It might even be from the victim. Maybe your victim was bullied or beaten at a suspect home and your investigator finds the print on the floor. You can get pretty creative but the smoother and harder the surface the better. You could even consider having a latent blood ear print that is developed with Luminol or some other reagent. Whatever you decide, have some fun with it and maybe build up some controversy over the use of the print in the investigation.
Author John Grisham Taken To Task by Forensic Scientists
There is an interesting article recently released by The Crime Lab Report in which the editors take New York Times Best Selling Author John Grisham to task over statements he gave while testifying before a Senate committee of the United States Congress. Mr. Grisham’s statements do seem puzzling given the testimony cited from the trial but in his defense he may have been working off of someone else’s data (and I am only going off of this report). Nearly all of the methods and practices of the forensic sciences were utilized or discovered in other scientific fields long before they were ever applied to criminal investigations. Additionally, they have been “subject” to peer review from the scientific community for as long as they have been in existence. In many cases this is over a century! The main thing I take away from the article, and the debate, is that sometimes it’s the attorneys who misrepresent forensics, not the scientists (although that happens too).
I am always amazed that as an expert witness I have to go through voir dire and demonstrate to the court that I am an expert before giving forensic testimony to the jury. However, a lawyer can simply say “the evidence will prove…”X” without objection during opening and closing statements. Granted they are not giving “testimony” per se but the jury still hears the statement. Lawyers are intelligent professionals and can have great sway in convincing a jury of their particular point of view (that is their job after all) so it is interesting to me that they can effectively give their opinions on the value or weight of forensic evidence without ever proving they have the expertise to make such claims. I’m not sugesting lawyers be held to the same standard mind you, but it is a reality of the judicial system in the United States. Anyway, just some interesting reading.
http://www.crimelabreport.com/library/monthly_report/2011-1228.htm
Touring the Crime Lab: The General Examination Room
FBI Crime Lab; Quantico, Virginia
This posting will be the first in a series of articles providing you a peek inside actual working crime labs. I have been to crime labs all over the United States, big and small, and I can tell you they bear little resemblance to the ones you see on television. First a few things about crime labs in the United States. They can be as varied as the individuals working in them. I have seen “labs” that were nothing more than a short counter top in a small windowless room. Other labs are 20,000+ square feet filled with the latest and greatest equipment costing millions of dollars to operate. Another big difference with abs on television is that access is very restricted.
For our purposes let’s divide them into two broad categories; full-service and varied-service. Full-service is, as it sounds, laboratories offering all the services one might routinely use in a major investigation such as DNA, firearms, chemistry, microscopy, etc. Varied-service laboratories offer some services but not others (like DNA). Typically this is due to cost but it may also be cultural (we’ve never had a footwear examiner so why start now) or due to an inability to justify the cost. For example, if your state crime lab will do all the DNA testing for your organization at no charge some managers may not see a benefit to building a DNA section.
Another factor is jurisdiction. The United States is by design a Federalist system of government. Large municipalities will have higher densities of people, larger tax base, and hence more money for providing services. Small townships or municipalities will have fewer funds and generally less serious crime. We also have State and Federal laboratories having jurisdictions over certain types of crimes and investigations. It sounds very complicated but in reality we make it work pretty well. The point is that a large metropolitan area may have dozens of crime labs (different agencies in different jurisdictions) operating and offering different services. Each state will have a full-service laboratory that will handle the testing the smaller agencies can’t.
In this series of articles I will be showcasing newer facilities having between 2-10 employees. Postings will be from different laboratories but they will represent what you might expect to find in any given modern laboratory. Just remember that when you are describing a laboratory in your area consider your jurisdiction. A small community of 5,000 people will likely not even have a crime lab.
The General Examination Room:
Laboratory space (rooms) is often created to perform certain tasks. The general examination room is a place where evidence is evaluated. It really is a mulch-purpose room where the CSI may take measurements, photographs, notes, etc of the general condition of the evidence. This is a space where evidence is examined before any specialized testing or photography is done. For example, you have to examine a shirt before you’ll know if there are any bloodstains on it requiring testing. Butcher paper is commonly found in these rooms because new sheets are rolled out for each item of evidence examined. This prevents trace evidence from contaminating the work surface.
Note the large stainless steel tables and numerous cabinets
A good examination room will have large movable tables that can be combined to give a surface area large enough to hold a king sized mattress or sheets. There will also be a lot of counter space. Not just any counters either. Counter tops are typically either stainless steel or made from chemically resistant materials. We work with acids and other hazardous materials that would ruin most Formica type counters. The walls may even be covered with washable plastics similar to what you might see in a restaurant kitchen. There are generally a lot of cabinets to hold all the various equipment and packaging supplies (boxes, bags, containers, envelopes, etc) and tools we use to do our examinations.There will likely be fume hoods and a sink as well as safety equipment like an emergency eye-wash station and shower.
Emergency eye wash/shower and butcher paper rack
Sink with chemically resistant counters
Hopefully the photos will give you a little perspective on how a “real” crime lab looks. Feel free to take some license when describing your laboratory but recognize some of the “function” to each section. In a few weeks I’ll post the next installment and we’ll keep going until you get a pretty good picture of the modern crime lab in the United States.
Notice the long counters with power strips and anti-fatigue mats on the floor
Various footwear lifting supplies
How Are Shoeprints Compared? The Overlay Method
Some suspects may wear latex gloves to commit their crimes but I have yet to meet one who wears shoe covers. And, since they can’t fly into a crime scene there’s a good chance that police can recover footwear impressions from the suspect. There are a variety of methods CSIs can use to lift or cast shoe impressions from a crime scene. In addition to photography, there are various adhesive or electrostatic methods that can be used. Ultimately, we want to recover the impression so that we can compare the class and individual characteristics that may make that shoe unique.
In most urban areas police find a predominance of two-dimensional shoe impressions. In a given day, most of us travel much further on hard surfaces lice cement, tile, wood floors, etc than we do in soil or snow. So when a CSI recovers a two-dimensional shoe impression how do they go about comparing it? First we need the suspect shoes. Decades ago, examiners would photograph the outsole of the shoe and compare the photograph and the lifting sheet side by side. Not surprisingly, this was referred to as a side-by-side comparison. It was laborious and there was a greater chance for error when comparing measurements.
In the 1980′s companies developed the transparent lifter. There are a number of products and processes that can be used so for our purposes let’s just say these are transparent plastic sheets that allow CSIs to reproduce an image of the outsole. One of the most common processes is to coat the bottom of the shoe with a layer of black fingerprint powder. The examiner then puts on the shoe and steps onto the lifting sheet, thereby imparting the impression on it. Having a transparency of the impression allows the footwear examiner to overlay the known shoe impression over the crime scene (question) impression.
Powdering the outsole
This method provides much greater accuracy in the comparison because the examiner can more easily compare the physical size and spatial relationship of each element in the impression. Think of it like having a tracing on velum or wax paper of an original drawing. While the examiner has to account for any distortion, this method makes it easy to distinguish slight differences that may exist between the two impressions. Examiners can also see if small defects or damaged areas line up as they should.
Covering transparency film with protective sheet
One mistake new examiners make is not labeling the transparency sheets correctly. As you might imagine, a transparency can easily be flipped over. If you don’t know the impression is from the right shoe then simply turning it over might make it appear to be made by the left shoe. For this reason examiners should note on each lift which shoe made it as well as other pertinent case information.
Bad Santa: Uniforms, Costumes, and Perception
Today I have a new posting at the Crime Fiction Collective on the use of uniforms in character development. Our perceptions and paradigms regarding uniforms can be quite powerful and may actually influence behavior of your characters (just as they do in real life). Authors should consider these factors when using uniforms in their crime stories. Check out the full article here.
Gun Talk Radio Podcasts: Interview on the Criminal Mindset
- Image via Wikipedia
One of the most informative weekly programs on gun-related issues I have found is Tom Gresham’s Gun Talk Radio program. Every Sunday for three hours Tom covers a wide range of issues relating to firearms and the shows can provide a great deal of insight into gun owners, gun activists, and the latest on gun technology. As a writer you can learn a lot from these podcasts for both character development and accuracy on the technical aspects of firearms. Unlike some talk show hosts on this subject I have found him to be very polite and reasonable with callers.
Tom Gresham has a long career as a writer and is a brief bio from his website;
Tom Gresham’s entire life has prepared him to be the host of Gun Talk®. He has been shooting since the age of six, deer hunting since 11, and at the age of 13 he was taking photographs for the best-selling book The Complete Book of Bass Fishing, written by his father, Grits Gresham. By the time he was 18, Tom was co-author (with his famous father) of a syndicated newspaper column. At 23, he was the editor of Southern Outdoors Magazine. Other outdoor magazines he has edited include American Hunter, Alaska, Handloader, and Rifle. Tom also has written several books, including Weatherby: The Man, The Gun, The Legend.
Yesterday he had a very interesting interview with 36 year police veteran Dave Spaulding on the criminal mindset as it relates to personal protection. You can listen to the broadcast here. Dave brings up some important issues about how criminals choose their victims. If you are looking to beef up your knowledge of firearms related topics I highly recommend the show.
Recovering Erased Marks from White Boards
Erased Dry Board
If you work in an office or school you probably use a white “dry-erase” board. These are commonly found in a variety of settings for presenting information to a group and keeping it posted temporarily. These modern chalkboards offer the advantage of multiple bright colored inks that can be easily erased with a common chalkboard eraser pad. In fact, police agencies frequently use these boards in a “war room” to keep track of changing information during the initial hours of a major investigation. When the case is over the board is erased. To the naked eye it would appear that the information is permanently lost but to the trained CSI it is merely “hidden”. CSI’s love hidden evidence because it represents a challenge; kind of a dare on behalf of the criminal.
You see, some criminal organizations use dry-erase boards too. It might be a chop shop dealing in stolen vehicles, an illegal drug operation or prostitution ring keeping track of customers, financial, or operational (names of prostitutes and locations) information. Sometimes the information may be patently criminal, other times it is merely another lead to be followed up on. But when the police pound on the door rest assured a criminal will be erasing the board and the information on it. In that moment they believe they have destroyed the incriminating information.
A well trained CSI however, knows that the information is just waiting to be uncovered. You see, as the marker ink sits on the board it forms a “film”. The longer the ink stays on the board the more hardened the film becomes. When the suspect passes the eraser pad over the writing they are merely wiping off the “color” or pigment. The simplest method to develop the latent film is by the application of standard fingerprint powder with a brush, just like you would process an item for fingerprints. The best part is that the dark fingerprint powder contrasts very well with the white board making photography much easier.
Developed Writing with Black Fingerprint Powder
This processing can be done many months later as long as the board is not wiped with a liquid cleaner. This gives your detectives time to possibly chase other leads or have your protagonist come in later and save the day by discovering the evidence right in front of them. You may even use something like this as an explosive scene in a courtroom drama by exposing the new evidence mid-trial! Play around with some options and have fun with it.
What’s In A Rape Evidence Collection Kit?
Whenever a rape victim gets examined there are various types of evidence that are collected from him or her. Sometimes victims don’t remember the extent of the assault and so CSIs usually collect a variety of samples just in case. Nowadays, many victims are examined by a forensic nurse (one specifically trained in the collection of such evidence) at a hospital but in some cases the victim may be examined by a same sex detective or officer in rural locations. Obviously these samples may also be collected at autopsy if the victim is deceased. In order to ensure some consistency in the collection process the sexual assault kit was created. While various commercial kits may have slight differences most will have the following at a minimum.
Tweezing head hair
Swabs:
A swab is a sterile cotton tipped applicator (like a Q-Tip) that may be moistened with saline or distilled water (or used dry) to rub in various areas to collect DNA evidence (sperm, blood, skin cells, etc.). Typically two swabs are rubbed on the area at the same time. This is necessary to have a second swab available for additional testing by the defense or in the event the first swab is contaminated. Sometimes more than two swabs are taken. Swabs come in separate packages labeled with the area to be tested which will include vaginal, anal, and oral. Swabbing may also be done of nipples, bite marks, or other body parts containing possible suspect DNA. Some kits also contain microscopic glass slides where samples from the vaginal or anal cavities will be wiped for microscopic examination (since they are collected from “wet” locations). Deceased victims may also have their nostrils and ears swabbed for trace evidence but this is rarely expected to be of a sexual nature.
Cuttings and Scrapings:
In addition to swabs some kits have containers for fingernail clippings (autopsy) or scraping with a disposable tool called an orange stick. Rape victims may scratch their attacker leaving his skin cells under the nails. Orange sticks are wooden and about the size of a small pencil but I suppose plastic versions exist as well. Sometimes (especially in the pre-1990′s) a similar device was used and simply cleaned between scrapings. I have also seen pathologists use toothpicks in the past. Today, disposable instruments are quite common. Most kits have envelopes or containers to separate the evidence from the right hand and the left hand but sometimes they are combined.
Combings and Tweezers:
Kits will also contain disposable combs and tweezers to collect various hair samples. For example, the CSI will comb the pubic hairs (if they are present) and head hairs for any suspect hairs that may be co-mingled. CSIs will also take samples of the victim’s hairs from various regions of the body for comparison to any hairs found on the suspect or at the crime scene. Hairs from different locations (head, pubic, etc) will be kept separated in different envelopes or containers.
Containers:
Most kits contain various coin or standard (business size) envelopes for hairs. In older kits it was common to have paper sheets that were folded into “bindles” or hand-made envelopes. Small plastic jars may also be used for various trace evidence. Swabs can be placed in envelopes or small cardboard boxes (about 1/4″ x 1/4″ x 8″) which are also labeled as to where the swabs were collected from.
Knowing what is in a kit helps you understand the type of evidence that is searched for and how it is collected. As an author this gives you a bit more detail to work with in creating scenes and dialog.
Shot Through the Heart…or the shoulder, or something.
This is an issue pertaining more to movies and television than novels but it still has relevance. I’ve written before about the need to pay attention to certain details. Like a lot of CSIs and authors I pick up on certain editorial errors I see on film. The other night I was watching the ending of a show entitled The Walking Dead on AMC. If you’re unfamiliar with the show its basically about a small band of humans trying to survive after most of the world’s population is turned to zombies. As you can imagine the surviving humans have to kill the zombies as they encounter them. So in this one particular scene the humans are gathered outside a barn filled with zombies. As the walking dead come out of the barn the humans shoot them. Sitting there watching one zombie drop after another I found myself asking “why do they keep shooting them in the left side of the chest?”
I don’t mean to pick on these writers as you can find this gunshot injury in a lot of films. It seems like even the most elite soldiers and law enforcement officers aim for the left shoulder. The reason is silly, but understandable. In the United States children are taught to place their hands over their hearts while reciting the Pledge of Allegiance. If you watch children and adults at sporting event they will place their right hand over the left side of their chest. This is exactly how I was taught. Apparently, sometime in our history we were taught that our hearts were on the left side of our chest.
In reality, our hearts are in the center of our chest. Apparently, no one has bothered to tell many directors. I have yet to read a novel making this mistake but, in truth, I haven’t read as many novels as I have textbooks. If you look at a typical human sized target silhouette found on a shooting range you’ll notice that the center of scoring ring is actually in the center of the chest where the heart is located. Police officers and competitive shooters don’t get a lot of points for shooting the left shoulder.
When writing a scene you could have a shooting victim survive because they were shot on the left side of the chest. Your characters could dialog about how lucky they are and discuss some of the reasons mentioned above. But if you want to maintain accuracy (pun intended) in your writing remember that when police or military aim for the heart, they should be aiming for the center of the chest.
The Five Stages of Decomposition
Maggot mass on dead pig
Following death, the human body progresses through five basic stages of decomposition. The duration and degree of each stage is largely influenced by the environment (temperature, humidity, etc.), body mass, any wrappings or coverings of the body, and obviously scavenging or other post-mortem disturbances. Additionally, submerged or buried bodies will decompose much differently than bodies left on the ground. This is what I will be referring to below. Here are the general descriptions of the five stages of decomposition:
Fresh:
The fresh stage begins immediately after death when the circulatory system (heart beating/pumping blood) stops functioning. It is during this stage that the blood will settle with gravity creating a condition known as lividity. After several hours the muscles will also begin to stiffen in a process known as rigor mortis. The body temperature will also begin to acclimate to the environment. Cells will begin to break down and release enzymes during a process called autolysis which can cause blisters on the skin. The anaerobic organisms in the digestive tract will begin to multiply, producing acids and gases (the source of the bad odors). This process is often referred to as putrefaction.
Bloat:
As the name implies, the gases being produced during putrefaction begin to build and will give the body a distended appearance. Gases and fluid will eventually escape through the natural orifices as the pressure builds. As the gastrointestinal bacteria multiply and can lead to conditions like marbling which is a discoloration pattern seen in the skin. You may also see green discoloration in the abdomen areas and eventually a darkening (blackish) coloring of the skin overall as the process advances. Interestingly enough; I remember one time I was giving a lecture on forensic entomology at a college campus and after the lecture a serious looking young black student approached me. She asked me why I only showed pictures of black victims in my presentation. I was a bit taken back and briefly confused as I ran through a mental recap of the cases I presented. I finally told her that all of the victims were in fact white (Caucasian) in life but due to this process their skin darkened. It was an eye-opening experience and I made sure to describe this process more effectively when lecturing the public.
Marbeling on tissue
Active Decay:
During his phase the body begins to lose much of it’s fluids and mass (tissue) through purge and insect and/or vertebrate scavenging (coyote, fox, lion, etc). During this phase you may see very large maggot masses and notice a considerable increase in foul odors.
Advanced Decay:
This phase is the end of the active decay process. Temperatures can either speed up (heat) or slow down (cold) how quickly a body reaches this phase. The body has very little body mass and soil staining of the surrounding soils is still evident. This soil staining (from body fluids) may actually kill some of the surrounding vegetation temporarily. Maggots will migrate away from the body to pupate and flies will cease laying eggs.
Dry/Skeletal:
This phase is the last measurable stage of decomposition. The timing of this stage varies widely by environment. For example, a body in Florida in July (hot/humid) may reach this stage in a week while in the Winter in the Rocky Mountains (cold/arid) it might take months. If there is any skin left it will be leather-like and very tough. Mostly the body is reduced to bones and connective tissue. There is no biomass available for diverse insect colonization. Some beetles and adventitious insects may colonize a body for shelter or feeding on other insects and connective tissue. Over time the bones may “bleach” (turn white) with exposure to sunlight and eventually will begin to exhibit cracks after several years. These weathering cracks are distinctive and would not be confused with a fresh break (injury) unless by an inexperienced analyst.
Advanced decay stage on ribs
Knowing or describing the correct stage of decomposition is not a critical issue for most authors. However, if you plan on describing the state of the body it would be wise to give the reader a little information to justify the scene. For example, if your victim has been missing six months but still has visible tattoos on their remaining skin, reasonable readers are going to wonder how that is possible. One way to address that is through dialog. You could have one detective comment to the other about the extremely cold winter they have had and how fortunate they are that the cold weather helped preserve the evidence. Readers will give you quite a bit of wiggle room but recognizing when your timeline crosses these stages will help keep your writing realistic and your readers happy.
