Sniffing the Air

by Andrea Campbell

Most everyone I talk to is upset or depressed over the Casey Anthony case, which just recently found her not guilty in the death of her child. Since you would have had to been living in a cave to not know about the case, I will assume you are upset as well.

There is a lot to talk about the forensic evidence in this case, and what for me seems like quite a lot of evidence for a case of this type. But almost all of it seems to be controversial in one way or another. Since I write to you in colloquial terms—as if speaking to a friend—I try not to use terminology that is science jargon, and tend to explain things simply and in a way that anyone can understand.

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Types of Evidence
The first important element we can discuss is what types of evidence are used in a court of law. There are more than you may know: direct, circumstantial, biological, reconstructive, associative and, individual or class characteristics.

Direct evidence is thought of as established fact. These are generally eyewitness statements or confessions.

Circumstantial evidence is not absolute proof but provides general knowledge and if you connect the dots, would seem to make sense or act as a logical conclusion. Typically, forensic evidence falls into this latter category. To folks in the criminal justice industry though, forensic science is generally more reliable than direct evidence because eyewitness testimony is sketchy, with people unable to recall events or positively identify suspects.

Biological evidence is anything that comes from a living organism and, in this case, would be the hair found in Casey Anthony’s trunk—this evidence type stems from body functions or fluids shed at the scene.

Of course, physical evidence can be found on inorganic items and some examples are: fingerprints, tool marks, paint, firearms and so on.

Reconstructive evidence helps an investigator figure out the five clues: who, what, where, when and how. The door that was pried open tells us how the perpetrator got into the house for example.

Associative evidence is what ties the suspect to the crime scene. The Casey Anthony case could have been made a lot easier if fingerprints had been found on the duct tape that covered toddler Caylee Anthony’s nose and mouth.

And the typing of evidence, either individual or differentiating is referred to as class characteristics. It follows that anything that is individual, can be narrowed down to one person or calculated as belonging to a very small group of people. The principle used to analyze materials and come to the assumption that it is individual is that no two things are exactly alike. A pair of shoes will exhibit characteristics when worn, unlike any other—so if those shoes leave a print impression at a crime scene and they are later found in the suspect’s closet, that leaves them open for an individual characteristic.

Differentiating class characteristics, on the other hand, could be the type of bullet that came from a gun. The caliber matched to a gun could make for a possible murder weapon. A found .38 caliber bullet means the weapon size is the same, so a .38 caliber bullet differentiates it from a shotgun.

Experts thought the forensic evidence in Anthony's car would be pivotal evidence for the murder trial. The car tested positive for chloroform and human decomposition and a strand of Caylee's hair was found in the car's trunk. Also, a cadaver dog, Gerus,—trained to find human remains—alerted on Casey Anthony’s car, a Pontiac Sunfire, and his handler testified to that occurrence.

Forensic Air Testing
Today we will talk briefly about the air testing in the car trunk. The forensic community has been using air tests for a long time. The science of chemical detection is forensic toxicology and is a means to separate and analyze chemical substances. The best example of common testing is when law enforcement uses a Breathalyzer to determine the blood alcohol content in a drunk driver for example.

The Smell of Decomp
"Once you smell it, you will never forget it." This comment and others comes from a site that has anecdotal comments from police and others whom have all smelled death. Human decomposition is a permeating smell and is often said as “hard to describe” but that doesn’t mean it isn’t distinctive. When Dr. Arpad Vass went on the stand to testify about the air samples taken from Casey Anthony’s car, I assumed that evidence was more than compelling. He spent a lot of time explaining his expertise in research about the smell of human decomposition. Vass works at the Oak Ridge National Laboratory in Tennessee where he analyzes the odor of death by working with cadavers at a 3-acre body farm, specifically used to study death and decomposition.

According to an ABC news report, "He [Vass] is essentially working towards finding a signature for human decomposition that will lead to the creation of an electronic detector that does the work of a cadaver dog. His research is already being used by the FBI to create a database of the chemical compounds found in human decomposition."

Vass said that the air samples taken and preserved in a can from the trunk of Casey Anthony's car had an abundance of chloroform, a sign of human decomposition and a chemical that also can be used to commit murder.

"I essentially jumped back a foot or two… I was shocked that that little itty bitty can could have that much odor associated with it… I would recognize it as human decomposition," Vass told jurors.

The Body in Death
"After we die and the bacteria proliferate in our body and start breaking down our muscles and our fat and organs, vapors, gases, are formed with beautiful names like cadaverine and putrescine that are a particular structure that are easily picked up in the toxicology lab if they’re collected from the area, the air that the body was in," said respected forensic pathologist Dr. Michael Baden. "If there was a dead body in the trunk of the car and they collected the air sample, they should be able to find those chemicals."

Entomology Report
In addition, flies and fly larvae found in the trunk of Casey Anthony's Pontiac suggest that the body had been decaying there for three to five days, according to testimony by an insect expert. The entomologist believed that Caylee's body had already undergone a brief period of decomposition before it was put into the trunk, and he cited the presence of a gnat-like fly that appears only after a body has started to decompose. This testimony rebutted defense claim that bad smells people reported could have come from garbage, but it turns out the same type of fly is not attracted to household trash.

New Science Questions

Dr. Lawrence Kobilinsky, head of the Forensic Sciences Department at the John Jay College of Criminal Justice, told TIME. "It's what the state calls 'state of the art.' It's what I call 'not ready for prime time… It's not junk science, but it never should be brought into a courtroom at this stage.”

I disagree. Most cases today are decided on circumstantial evidence. There was enough forensic evidence—dueling experts or not—to come to the correct assumption and connect the dots. Casey Anthony's car was a crime scene. And I think the jury just wasn’t listening and strained (and failed) to understand the principle of reasonable doubt. What do you think?

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That Murky Question: Time of Death

by Andrea Campbell

You would think time of death would be something rather elementary. But it's actually a complicated concept and there are a lot of variables. The legal time of death is what appears on the death certificate. When you watch those hospital shows and they look at the clock and announce the time, that's a legal death notification.

Estimated Time of Death

This is what you're going to get from the medical examiner and it is his/her best guess for the present situation.

Physiological

This marks the time when the victim's vital organs for sustaining life cease to function.

The basic time of death estimation should be given when and where the body is discovered, before it gets photographed, moved, and transported. A medical examiner (or coroner, depending on your jurisdiction) will try to “guesstimate” the approximate time the person died based on several factors. In her article for Crime Library, Katherine Ramsland tells us that time of death is one of the central factors in any murder case because it can eliminate suspects, break alibis, or place victims clearly with the suspect. That's a given. Not to mention that it helps to form a timeline, giving detectives important clues as to what could have happened when. Time as an element in an investigation has the greatest potential for leads, other than a confession of course. People usually run their lives on routine, so by figuring out how long they've been dead, helps an investigator to question friends and family; in essence, he asks: Where should they have been? Doing what? Why? With who else?

Here is a short descriptive list of what is looked at in part or in whole to help determine time of death:

1. Body temperature, also called algor mortis—a body cools when oxygen no longer is being pumped through to help keep a normal body temp of 98.6 degrees Fahrenheit. The rate is approximate, but a rectal temperature reading is divided by 1.5, which is equal to one to one and a half degrees per hour since death, when the body takes on the temperature of its surroundings.

2. Discoloration from livor mortis, also referred to as lividity or hypostasis—in a dead body the fluids settle, and a dark purple color is found on the lower side where it is lying. It happens because the white and red blood cells don’t mix anymore and the reds are settling. If part of the body is lying on a grate, that pattern will be repeated on the tissues because the contact makes pressure and keeps the blood from pooling there. A phenomenon called “blanching” (press your finger to your skin, it leaves a white trail) can indicate that lividity is not permanent, and that death is probably more than two hours old but not as long as ten. Two factors may change blood color, carbon monoxide poisoning (presents a bright red color) and extreme loss of blood (no discoloring at all).

3. Food digestion—examination of stomach contents can time date when someone has eaten their last meal, and the death estimation is based on the fact that the stomach breaks down food and empties it into the intestines at a fairly predictable rate. There are many factors that can play into this determination, however, including metabolism, drugs, medication, presence of disease, and the person’s emotional demeanor.

4. Rigor mortis—this action is due to muscles stiffening on account of accumulating waste products. It generally begins a couple to three hours after death and seems to start in the face, lower jaw and neck, and then spreads over the next twelve-plus-hours up to about eighteen hours to the larger muscles in the body. The rigidity can last up to thirty-six hours after which it then begins to disappear, starting at the head and face again. This process too, is affected by temperature (heat speeds the process) and differences in musculature (if not much muscle, less stiff).

5. Decomposition and decay—a dead body builds up fluids and gas due to the microorganisms that live inside. Liquids can emanate from the mouth and nose, the tongue swells, and the abdomen turns a greenish-yellow color. Over time, the skin will blister and fill with fluid. The decomposition process is sped up by heat and slowed under colder conditions. "Decomp" attracts insects as well and they set about the body to feed and lay eggs (usually in the bloody areas first). Their larval stages are what help to predict death. Bare in mind, Dear Reader, that forensic entomologists are a rare species themselves because there are probably no more than seventy certified forensic professionals in the whole of the country.

6. Ocular—eyes that are left open after death will develop a film on the surface. The red blood cells break down here too (in the “vitreous humor”), and the eyes after two or three hours will appear cloudy. Cloudiness shows in closed eyes as well, but much more slowly.

7. Personal factors—people are a great source of time death estimation as in “the last time I saw so-and-so . . .” ; those missing an appointment help to pinpoint time, a broken watch or timepiece will help, or a time-date from a camera are other considerations.

8. Other scientists—a forensic botanist may be able to give time-date clues based on the presence of pollen, pods or whatever vegetation growth or stunting may have occurred beneath or around the body; forensic anthropologists can help add notes after skeletonization, and toxicologists will have something to say about the fluids and blood.

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Further Reading:

Time of Death, Decomposition and Identification: An Atlas by Jay Dix, M.D. and Michael Graham, M.D., CRC Press, January 2000. ISBN: 0-8493-2367-3

Forensic Pathology by Dominick J. DiMaio, M.D. and Vincent J.M. DiMaio, M.D., CRC Press, June 2001, ISBN: 0-8493-0072-X

Corpse: Nature, Forensics, and the Struggle to Pinpoint Time of Death by Jessica Snyder Sachs, Perseus Publishing. (Have not reviewed as yet.)

http://www.crimelibrary.com/forensics/time/

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Cadaver Dogs: Canis Familiaris

by Andrea Campbell

Cadaver dogs are canines, Canis familiaris, which are specially trained to find human decomposition scent and alert their handlers to its location. They are used in a variety of forensic contexts, including search and discovery of human cadavers, body parts, or body fluids. In contrast to bloodhounds or other tracking dogs—which locate a specific scent on the ground or an item—cadaver dogs are trained to detect generic scent in the air.

In particular, these dogs are conditioned to give an alert to the scent of human decomposition. They are sensitive to the odor given off by newly dead bodies, which may lack any obvious signs of decomposition. They will also alert to decomposing bodies, to skeletal remains, or even to soil contaminated with human decomposition fluids. Because of the sensitivity of air scent dog olfaction, even buried bodies or bodies dead for 20 or more years can be detected in certain circumstances!

History

The first dog trained exclusively for cadaver search by a police department began work in 1974. The NY State Police were investigating a homicide in Oneida County that involved multiple buried victims in a large forested area.

Increasingly, the cadaver dog/handler unit is part of a multi-disciplinary search team including medical examiner, anthropologist, and law enforcement members, among others.

Dog Selection and Noses

If the dog is chosen solely for air scent work, the principle drive is the prey drive. Basically, you should look for a dog that is “ball crazy.” The dog should follow the movement of the ball. . . . A dog that is adaptive to new sites, one that is not startled by loud noises and recovers easily, are good traits.

All animals directly sense chemical molecules. This is true even in animals that lack a nose. Bacteria are known to sense and cluster about certain chemicals. Flies sense molecules through their feet. Human beings have approximately five million olfactory receptor cells. A bloodhound has 100 million such cells.

Scent Cone Theory

Scent is produced when molecules from an object are dispersed into the air and register a sensory reaction in the brain. Molecules shed by the object become more and more dispersed the farther away from it they move. This concentration gradient theoretically forms a scent cone. Mammals are able to detect both the presence and the relative concentration of scent. Interruptions to, and enhancement of, the spread of molecules from the source may distort the scent cone.

Decomposition Process

The decomposition process commences immediately after biological death occurs and proceeds through five stages before the body is completely skeletonized. Certain elements are necessary for the process to occur. These elements affect how rapidly the remains proceed through the stages. The decay process produces a variety of gases, liquids, and acids. It is these by-products that provide the odor that the dog is trained to recognize and indicate. There are two special situations with different scent results: If a body decomposes in a wet environment, the adipocere, a grayish, soapy substance provides a good scent picture to the dog. If the body is left in a hot, dry environment it will mummify, and the odor will be musty, also recognizable by the animal.

Stages of Decomposition and Odor Characteristics

1.) FRESH: Little or no exterior change; however, is decomposing internally due to bacteria present in the body before death. Odor: None detectable by humans; however, animal may show reaction or approach body as if it were still alive. Dog may detect at some distance.

2.) BLOATED: Body swollen by gas produce internally. Insect activity may be apparent. Odor: Decay odor present. Detectable by bot dog and human. Can be detected at a distance.

3.) DECAY: Body collapses as gas escapes. Exposed flesh may be thick. Odor: Strong putrefaction odor detectable by dog and human at some distance.

4.) LIQUEFACTION: Liquids created during the decomposition process seep into the environment. Body drying out. Odor: Reduced odor production. May smell cheesy or musty. Animal may still detect at a distance.

5.) DRY/SKELETAL: Slow rate of decay. Remaining flesh may be mummified. Odor: Musty odor. Detection distance shortened.

*Detection distance varies with wind direction, weather and terrain. If approaching upwind, detection distance will be much greater than if working with wind at the handler’s back.

Elements of Decomposition

Microorganisms: Normally present in the lungs and intestinal tract. Many are necessary in a living person for normal functions. If death is the result of disease, pathological organisms may be present.

Warmth: Decomposition is significant at approx. 50°F and proceeds most rapidly between 70° and 100°F. Between 100° and 212°F, the process slows as the reproduction of bacteria is retarded by the increased temperature and moisture is evaporated.

Air: Oxygen-consuming organism activity is retarded by the absence of air. Restriction of airflow around remains will slow the decomposition process.

Moisture: Microorganisms require moisture to function. A body normally contains enough moisture for the bacteria to multiply.

Principles of Scent Cone Presence and Distortion

1. Decomposition odor will tend to form a scent pool above and around the remains.

2. Air flow will move the scent away from the source in the direction of the wind, forming an air scent cone.

3. Water will move the scent away from the source along scent conduits in response to gravity or currents, along surface of underground waterways; or following erosion or drainage patterns.

4. Wind or water flow can be altered by scent barriers.

5. Water flow along a conduit can interrupt the absorption of scent into the soil near the remains causing a scent void near the remains at the dog-nose level.

6. Variable wind patterns can cause an uneven distribution of scent molecules in the air.

7. Elevation of the body with a horizontal scent cone can produce a scent void near the remains at dog-nose level.

Taphonomy

Understanding the natural processes that influence outdoor death scenes is vital to the success of conducting and interpreting searches. The study of what archaeologists and paleontologists calls “death assemblages” is termed taphonomy, which literally means the laws of burial, but can refer also to unburied bodies exposed on the earth’s surface. In other words, taphonomy includes knowledge about the process by which a body is transformed from a living being to dust—or fossils, chemical constituents, or mummified remains. In forensic taphonomy, we are concerned with the earliest part of that postmortem period.

Legal Issues

When conducting a search, a dog/handler team is, in effect, searching for evidence. Most of the legal cases regarding dog searches deal with drug seizures, but the principle under which the issues are raised apply equally to cadaver dog searches. The two primary areas of concern are the acquisition of evidence and the acceptance of that evidence by a court. Unless the search team is operating within the guidelines set down by the Constitution and the court system, any evidence located during the search may not be admissible at a trial.

• The Fourth Amendment of search and seizure is the applicable standard. No warrant will issue without probable cause.

What constitutes a search with a dog? The court decided in United States v. Place, that the activity of a drug-sniffing dog was unique. The dog only alerted if there was evidence of contraband. Therefore, the dog was only disclosing criminal behavior and a warrant was not necessary. No intrusion of an innocent person’s privacy would occur.

Many courts have allowed searches by air-scent dogs without a warrant when the search has been based on other facts that gave the police a reasonable suspicion. Courts, however, will not allow dogs to be used for general exploratory or dragnet-type searches. The decisions in these cases appear to be very fact specific. The court’s decision to allow lesser evidence or exigent circumstances to be substituted for the need to obtain a warrant remains unpredictable.

The issues above rarely occur in the context of cadaver dog searches. These searches are usually the result of prior investigation. Cadaver searches by their very nature will lack exigent circumstances except in the rarest of cases. Those cases will usually involve the suspicion that a vehicle either has a body in it or was used to transport a body.

The principle area of concern for cadaver dog handlers is the possibility of warrantless entry onto property where there is a justified expectation of privacy. Open fields are not protected by the Fourth Amendment. The surrounding area or curtilage—areas adjacent to structures—requires a warrant. With public land there are no privacy issues involved.

There you have it: the working cadaver dog.

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Buggers!

by Andrea Campbell

Forensic entomology, the study of bugs as related to death, is a relatively new science. In the past, investigators thought bugs were a nuisance, something to be washed away or disposed of as quickly as possible. But the relationship between dead bodies and maggots is nature’s way of recycling—the way a corpse becomes simple organic matter.

Death carries a universal scent that attracts hundreds of insects and other arthropods as they set about the body to feed and lay eggs (usually in the bloody areas first). The life cycles of the insects that take place on the deceased are fixed and precise. Those characteristics make it a good tool for investigators called forensic entomologists.

It’s funny then how a form of forensic entomology was practiced as early as the thirteenth century, yet took so long to come to fruition. Story has it that a murder in a Chinese village was the result of the victim being repeatedly slashed. Witness questioning was going nowhere. In frustration, the magistrate ordered all the village men to assemble, each bringing his own sickle. Standing in the hot summer sun, flies were attracted to just one sickle because of the blood residue and tissue fragments clinging to the blade and handle. Confronted with this evidence, the owner of the sickle confessed to the crime.

Insects have helped to solve many crimes. The unique activities of the insects, paired together with the arrival of different species and different forms of species, act as a predictable time-clock that can be traced backward for estimations. The order in which the insects arrive is called succession. Succession is the idea that as each organism or group of organisms feeds on a body, it changes the body and makes it attractive to the next group, and, so on. For example, within ten minutes after a body is dead in open air, flies arrive and lay thousands of eggs in the mouth, nose and eyes of the corpse. The eggs hatch into larvae, also known as maggots, in twelve hours up to three days and the maggots feed on tissues. Since maggots go through three phases on their way to becoming adult flies, the entomologist tracks their development and makes calculations backwards in order to determine the date and time the eggs were most likely deposited.

The Importance of Blow Flies

Blow fly eggs, collected from human remains and analyzed, can provide investigators with an accurate estimate of time between death and discovery and allow them to better target their investigative efforts.

Blow fly eggs are small (2 to 3 mm), whitish-yellow, and somewhat elongate. During warmer seasons they are easily visible to the naked eye found packed into natural body openings and wound sites in large numbers. During colder months, however, their numbers may be few and difficult to locate, buried within recessed locations. Blow fly eggs typically hatch within one to three days depending on species and environmental conditions. Dissection of egg samples and analysis of the stage of embryonic development may further depict the time since oviposition—creation—and, therefore, the time of the victim’s death.

Within 24 - 36 hours, beetles arrive and feast on the dry skin. After 48 hours, spiders, mites, millipedes, and wasps arrive to feed on the bugs that are already there. Entomologists today recognize six decomposition stages.

Bug behavior can also indicate whether the victim was killed indoors or out, during the day or night, in warm or cold weather, in shade or sun. Bugs scattered and laying dead near remains have also told the story of a women who died from a drug overdose. The cocaine chemicals within her body had been passed onto the bugs.

Case Story: Insect Trail

The body of a woman was found in a wooded area near the District of Columbia. There appeared to be no evidence of foul play but as part of police procedure, the scene was photographed. It was late summer and the dead woman was dressed in a tube top and slacks. Since her clothes were intact the possibility of a sexual assault was not taken into account.

Despite peaceful surroundings, her advanced stage of decomposition meant that the medical examiner would have a difficult task. The body had been lying out in the open for about ten to twelve days. Larvae were in the eyes, around the nose and mouth, in the chest area, and on the palms of both hands. The dead woman was identified immediately and because of the condition of the body, pressure was put on the authorities to release her corpse for a speedy burial. A limited autopsy indicated the cause of death was unknown and the body was turned over to the undertaker.

Typically, that would have ended the investigation, but one detective remained puzzled. The question about time of death bothered him. The victim had been reported missing a few days before her body was discovered on the trail, but the detective wondered, why was her body so badly decomposed? And because of the advanced decay, her autopsy had been less than exact. Finally, three years later, the detective contacted a forensic anthropologist, showed him the photographs and asked for a second opinion.

The anthropologist asked all the normal questions and studied the photographs. He told the detective that considering the time of year, the larval activity in the photographs was consistent with the medical examiner’s time of death estimate and asked if police had a suspect. The detective was dumbfounded. He explained that the lack of evidence for violence led them to rule out murder and they hadn’t bothered to look for suspicious persons.

“Of course there’s evidence,” the scientist said, pointing to the pictures, “You just showed it to me.” Because of his forensic training, he had immediately recognized the significance of the larval activity in the palms of the hands. In the pictures the surfaces on both arms were clearly free of maggots, but the flies had laid their eggs in the deep lesions across the width of her palms. This signifies the kind of injury that is associated with someone who is defending against a knife attack.

The detective was stunned. “But how can you be sure the hand injuries aren’t just something that happened when she fell?”

He pointed to the chest area in the top photo. The decomposition, he said, suggested something else. “Maggots don’t swarm like that unless they have something to feed on. . . . Look at the body, I think you’re going to find she was stabbed in the chest.”

After much persuading, the detective convinced other officials. Her body was exhumed by lantern light in the middle of a snowstorm. This time the examination was more complete. Soft tissue was simmered away gently for a clearer view. Unmistakable blade patterns were found in the bones of the hands and in the chest. A new death certificate was issued, and the manner of death reclassified to homicide. Homicides are one crime where there is no statute of limitations. As long as the case is unsolved, it is considered open to scrutiny and further investigation.

Excerpted from Detective Notebook: Crime Scene Science
graphic: Cleveland Museum of Natural History

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