Chapter 10
IN THIS CHAPTER
Outlining how bodies are identified
Finding answers in skeletal remains
Determining the time and cause of death
Using facial reconstruction and photographic techniques
Not every corpse that comes into the coroner’s office is conveniently carrying a driver’s license and Social Security card. All too often police are confronted with identifying an unknown corpse. In movies, this process usually takes only a few minutes of screen time, but in reality, it may take weeks, months, or even years. Some bodies never are identified.
The corpse in question may have been dead for hours, days, months, years, or many decades. An extended time since death and many other factors can complicate the identification process, which usually involves several different forensic disciplines and techniques, all of which are coordinated by the medical examiner (ME).
Neither Mother Nature nor time is kind to the dead. Not only is a dead body subjected to internal digestion (autolysis) and bacterial action (putrefaction), but extreme weather, insects, predators, and environmental bacteria conspire to destroy it.
If the body is more or less intact, its size, sex, race, scars and tattoos, facial features, dental examinations, fingerprints, DNA, and clothing may help authorities identify who it is. So an intact or partially decayed body gives the ME a great deal to work with and in many cases, a facial photograph of the corpse can be taken and compared with photos or descriptions of missing persons. Problem solved. However, when the body is skeletal, help from a forensic anthropologist, forensic odontologist (dentist), forensic artist, or all three may be needed.
Once a presumptive (possible or likely) match is made, family or friends may be asked to make the final identification. If no missing person matches the general characteristics of the corpse, descriptions and photos are circulated to law enforcement agencies and the media. To help in this regard, a forensic artist or anthropologist may be asked to sketch or computer-generate a best-guess likeness of the individual (more on this in the later section “Reconstructing Faces”).
Sometimes items buried with or found near the body are helpful. Clothing, jewelry, materials used in the burial, and other artifacts can point to who the deceased is. Finding a wallet or ID card is ideal, but even if that sort of information is found, the forensic team may be involved in the ID process if the person cannot be positively identified visually. Many other items, however, offer clues:
Distinguishing marks on the body, such as tattoos, birthmarks, and surgical or other scarring, often are helpful in suspect and corpse identification. Many are so distinctive that they alone supply positive identifying evidence. Could you mistake former Soviet President Mikhail Gorbachev for anyone else? Probably not, because the port wine stain on his noggin makes his face one of a kind.
Birthmarks are irregular and distinctive, making them perfect identifying characteristics. The tattoos and other body marks of arrested criminal suspects often are sketched or photographed as part of the booking process; however, this procedure is far from universal. If photos from a previous arrest exist, they can be compared with the body marks on a suspect or corpse.
Certain gangs boast their own tattoos, and many jurisdictions keep files of these tattoos. In California, for example, the CALGANG database stores such data, and often a query results in a hit, which leads to identifying the victim. If the deceased had a previous brush with the law, a former cellmate, corrections officer, or arresting officer may be able to supply a presumptive ID.
During an autopsy, the ME may discover that the deceased suffered from a disease or sports a scar from a surgical procedure. This information narrows the search for identification. If the victim has a scar from an appendectomy or gall bladder removal, for example, a search through missing-person reports for people who are the same age and sex and have the same medical history may lead to identification, particularly if the surgery was a fairly recent event. The ME often can determine the age of surgical wounds.
Certain surgical appliances provide another means of identification, because they are uniquely marked. The ME may discover through an X-ray exam or during the autopsy that the deceased had a hip replacement surgery, for example. The artificial hip is removed and examined for an engraved serial number, which then can be traced to the hospital where the surgery took place and ultimately to the name of the person who received it. Pacemakers, implantable defibrillators, heart valves, and other cardiac devices have traceable serial numbers.
Unless a corpse is severely deteriorated, fingerprints can be obtained and matched against known missing persons and national fingerprint databases. Fingerprints often lead to quick and absolute identifications.
Saline sometimes is injected into the tips of the fingers, causing the pads to swell and potentially reveal the friction ridges (see Chapter 5). Alternatively, skin over the pads of the fingers can be carefully sliced away, viewed under a microscope, and even photographed for matching purposes.
Everyone’s teeth are different. Although you and I may have the same number and types of teeth, their lengths, widths, and shapes show great variability. Missing, misaligned, and reconstructed teeth can be matched with dental records to establish an identity. Chips, furrows, and fillings add even more individuality to the patterns of your teeth. Today, dental records often are used to identify human remains. DNA also plays a role here as the pulp of the teeth often supplies DNA-containing tissues.
When faced with an unidentified corpse, the ME often makes a set of dental X-rays that can be compared with the most recent dental X-rays of a missing person. With a match, the identity of the body is confirmed.
The ME uses any and all evidence she can glean from a corpse in order to ID the deceased. Even stomach contents can be of use in rare instances.
DNA is also used in identifying unknown remains in many cases. But, like fingerprints, it is only useful if there is a DNA profile available against which it can be compared. DNA taken from the corpse’s tissues, or from bones and teeth in the case of skeletal remains, can often be analyzed and compared to DNA from a missing person — if it’s available. It can also be entered into DNA databases such a CODIS in the hopes of getting a “hit” — a match with someone who is already in the system.
Besides nuclear DNA, other DNA analyses, such as mitochondrial DNA, Y-chromosomal DNA, and familial DNA, can be very useful in these situations as each can narrow the possibilities. Each of these techniques is discussed in Chapter 15.
Sometimes a forensic team doesn’t have a complete body to work with. They may have only a skeleton (at best) or simply a single bone. In these situations, the expertise of a forensic anthropologist and a forensic odontologist usually come into play. They’re asked to answer several questions:
Any hope of identifying an unknown corpse rests with determining the deceased individual’s biological characteristics; age, stature, sex, and race narrow the field greatly. After these characteristics are determined, the search turns toward individualizing characteristics. The presence of bony evidence of disease, congenital defects, or trauma is important.
The first question that must be answered is whether the bones are human. Time and the effects of nature and predators can scatter and destroy portions of a skeleton, leaving investigators with little to go on and no room for assumptions.
Bones are more complex structures than you may realize. They have bumps, grooves, indentations, and other characteristics according to their function in the body and what species that body belongs to. The forensic anthropologist uses these features, as well as overall size and thickness, to assess the species of origin. Yet, even with years of experience, species identification can prove difficult.
When only bones are available, the forensic anthropologist can only make a best guess (which is, after all, a scientific opinion) about age, but that estimate is more accurate for younger victims than it is for mature victims. Teeth and bones in children and adolescents follow a predictable growth and maturation pattern. By assessing the stage of this development, a fairly narrow age range can be determined. Later in life, after the maturation process is complete, changes in the teeth and skeleton occur at much slower rates, thus leading to age assessments across much wider ranges.
You may think that simply measuring the skeleton from top to bottom provides its height and general build. When a complete skeleton is present, that’s entirely possible; however, more often only partial remains are found, making such measurements out of the question. Remember that height is but one part of your stature, which also includes body shape, bone thickness, and degree of muscular development.
The long bones (legs and arms) can help provide an estimate of height. Tables matching length of long bones to the expected height of the person from which they came are available to help in this regard. For example, height usually is equal to five times the length of the humerus (upper arm bone). Even fragments of long bones can be useful in determining stature. Other formulas have been developed to enable investigators to estimate bone length from fragments. Such estimates make possible a rough calculation of the person’s overall height.
The thickness of the bones gives investigators a rough idea of whether the person was of slight or muscular build, as thicker bones often indicate thicker muscles. The thickness may also reveal handedness, because right-handed people usually have thicker, stronger bones on their right side, and vice versa for southpaws.
Determining sex from skeletal remains of infants and children is more difficult than it is with adults because gender-specific changes in the skeleton don’t appear until puberty, after which male and female bones grow differently and begin to take on sex-identifying characteristics.
The overall size and bone thickness of the adult male skeleton usually is greater than that of the adult female. However, bone size and thickness is related to many things other than sex: Better nutrition and heavy physical activity lead to stronger bones regardless of sex. So the skeleton of a female who ate well and performed manual labor may look more like that of a male than the skeleton of a poorly nourished male who rarely worked physically.
Nevertheless, the thickness of certain areas of certain bones can be used to distinguish between males and females. In general, the diameters of the heads of the humerus (upper arm bone), the radius (lower arm bone on the thumb side), and the femur (upper leg bone) are larger in males.
The skull also offers useful clues to the sex of an individual. Male skulls tend to have more distinct ridges and crests and to be larger and thicker, particularly in areas where facial and jaw muscles attach. In addition, the posterior ramus (back branch) of the mandible (jaw bone) in males is slightly curved, but in females it tends to be straight (see Figure 10-2).
Caucasians tend to have high, rounded, or square skulls, straight faces, and narrow, protruding noses. The shape of the eye sockets is triangular. On the other hand, those of Negroid descent tend toward lower and narrower skulls and wider, flatter noses with prominent, protruding teeth. Their eye sockets are usually squared. Mongoloids have broad, round skulls with an arched profile. The eye sockets are round with wide facial dimensions. Blacks tend to have proportionally longer arms and legs than do Caucasians, while in Mongoloids, the limbs tend to be shorter. Caucasians also have a forward curve to their femurs (upper leg bones), while in blacks this bone is straighter.
The skeleton of someone with a mixed racial origin obviously shares the skeletal characteristics of its ancestors. This racial admixture frequently makes racial determinations impossible.
Estimates of the age, stature, sex, and race of the remains greatly narrow the search for the identity of the unknown person, but establishing the true identity requires much more information. Just knowing that the remains are those of a 12- to 18-year-old, 5-foot-tall, left-handed Caucasian female doesn’t absolutely identify the individual. Far from it. But these factors narrow the focus to a manageable number of individuals.
Other details that can be compared with medical records or X-rays of potential matches to make identification more certain include
Taphonomy is the study of what happens to the human body after death. How the body decays, if it does, and how it becomes skeletonized (deteriorated to the point that only bones remain) are areas of interest to the student of taphonomy. As you’ve seen so far in this chapter and can discover in Chapter 11, estimating the time of death may involve not only the forensic anthropologist and odontologist, but also an ME, archeologist, climatologist, botanist, entomologist, and others (Chapter 2 gives details about each of these positions).
When confronted with skeletal remains, the forensic anthropologist first works to determine how old the bones are. The answer is critical to any forensic involvement. Bones that are hundreds of years old have little forensic use, but bones that are between 2 and 40 or so years old may have significant import.
Estimating the time since death is never easy, and it becomes increasingly more difficult with each passing hour. Chapter 11 looks at determining time of death of more-or-less intact corpses, a task that falls within the expertise of the ME. With skeletal remains, the forensic anthropologist determines the approximate time lapse since the death occurred, using any or all of the following methods:
Chemical analyses: Measuring the nitrogen level in bones, which decreases as they deteriorate, is one such method. This kind of analysis is inexact, however, because the rate of protein and nitrogen loss is affected by temperature and moisture, the same two factors that most affect the decay rate of the body. Nonetheless, because a high level of nitrogen suggests that the bones are a few years and not several decades old, this determination can be of some help.
Another chemical measurement is based on different amino acids disappearing from bones at different rates. Analysis of fresh bones may yield as many as 15 different amino acids, but bones that are a hundred or more years old often yield only seven.
Bones that have been burned present special problems for the anthropologist. Direct exposure to the fire chars and blackens bones and may cause them to crack or splinter. Prolonged direct contact with fire can calcinate bones, reducing them to white ashes. Under those circumstances, an anthropologist may have only a few remnants to work with.
On the other hand, the texture and color of the bones provide clues about the intensity and the duration of the fire. Indirect or brief exposure to the fire may cause only yellow-brown discoloration of the bones with or without streaks of soot.
Occasionally, skeletal remains offer clues to the cause and manner of death. Fractures, fragmentation, and impact marks (dents and depressions) on the bone may reveal blunt-force injuries, indicating the victim likely fell or was hit with a blunt object. Sharp-force injuries, such as from an axe or knife, may show up as cut surfaces where the blade sliced into the bone. Metallic remnants from the weapon occasionally remain along cut surfaces. Similarly, gunshots may leave entry and exit holes in the skull, and gouges and other defects in the ribs, spine, and other bones. Finding a bullet or two among the bones helps. Measuring an entrance hole in a bone sometimes enables investigators to estimate the caliber of the bullet that caused the injury.
Tracking injuries to more than one bone or finding an imbedded bullet may also enable investigators to estimate the path of the bullet and thus determine which organs may have been damaged. Of course, blunt objects, knives, and bullets can lead to death without impacting the skeleton, and, unfortunately, many strangulations and most natural deaths leave behind no skeletal evidence, meaning that a skeleton may not offer any clues to the cause and manner of death.
One problem facing the ME is whether the bone injuries occurred around the time of death or at some earlier point in time. For example, a skull fracture that occurred years before death and one that occurred at the time of death mean two entirely different things. Fortunately the forensics team often can make such a distinction.
Bones left in nature undergo trauma from natural forces and from predators and can suffer fractures years after the victim’s death. Forensic anthropologists recognize postmortem fractures as such in large part because living bones possess moisture, living protein, and fat, and that makes them less brittle than bones from a long-dead victim.
Fractures to living bones tend to be spiral (twisting down the bone’s shaft) or greenstick (splintered, like when you snap a green twig in half). Desiccated (dried out) bones are brittle and tend to crumble more readily and break cleanly, usually parallel or at a cross section to the long axis of the bone. By examining the nature of any fractures, a forensic anthropologist may be able to distinguish premortem fractures from those that occurred postmortem.
Based on the timing and nature of skeletal injuries, forensic anthropologists and MEs sometimes can determine cause of death and perhaps even whether it was self-inflicted, accidental, or homicidal in nature. Determining the manner of death, however, is not always easy or accurate. When findings suggest that someone died from a skull fracture, determining whether the fracture was caused by a blow to the head (homicidal), a fall (accidental), or as the result of a fall brought on by a heart attack or stroke (natural) can be difficult.
Forget Michelangelo. For the poor victims who end up dead and unidentified, great artists are those who re-create faces based on skeletal remains. Whether through drawings, sculptures, or computer-generated images, these artists help identify a body by creating a likeness of the victim that is circulated in hopes of finding someone who can identify him. Facial reconstruction, or re-creating a likely image of the unidentified victim’s face, comes into play when other methods have failed to identify the remains.
The skull, or a casting of the skull, serves as the framework for this fascinating art and often must be constructed from just portions of a skull. Once this is accomplished, a drawing, clay model, or computer image is created one layer at a time. These sketches, computer graphics, and three-dimensional clay models require the hand and eye of an artist and a great deal of experience. Not to mention guesswork.
However, many problems plague this process. The structure of the eyelids, hair and eye colors, hairstyle, and the presence or absence of facial hair are not known. The victim’s race also is likely unknown, though DNA analysis can often suggest racial origin (see Chapter 15). Features such as the nose and ears, which are made of cartilage, are often absent. Drawing or sculpting these features requires the artist’s best guess. Similarly, the thickness of the skin and the amount of body fat also must be estimated, and any errors in these estimations can greatly affect the final picture.
Whenever the characteristics of a missing person fit the general characteristics of the remains, a photograph of the missing person can be superimposed with images of the skull to confirm an ID using a technique known as skull-to-photo superimposition. Basically, the photo of the missing person is superimposed over a similarly sized photo of the skull, and the bony landmarks are compared.
This technique rarely provides a conclusive match, but it can eliminate certain candidates. For example, the missing person’s photo can reveal eyes that are too widely spaced, a nose that’s too long, or a chin with a contour that’s different from the one on the skull. On the other hand, when all the features match, the missing person cannot be excluded.
When they’re not digging into bones, forensic anthropologists may be asked to use their knowledge of what lies beneath the skin to determine whether two photos are of the same person. Although everyone’s face undergoes age-related changes, certain features do not change, and the forensic anthropologist can compare the bone structure of people in photographs, even if the photos were taken years or even decades apart and vary widely in quality and technique. One photo may be from a surveillance camera and the other from a professional portrait studio, for instance.
The examiner superimposes one photo over the other and compares fixed structures, such as orbital ridges (eyebrow area), nasal openings, and chin contours. A match suggests that the photos possibly are of the same individual. Matching superimposed photos is not conclusive but rather is suggestive evidence.
A forensic anthropologist or artist may also be asked to age a photograph when a suspect or a missing person has not been seen for years or decades. Using an old photograph of the individual, an attempt is made to determine what the individual looks like years later. This technique has been successful in finding missing persons and tracking down suspects on many occasions. This aging process mostly is guesswork, but in recent years a number of individuals have gained experience and abilities, becoming quite skilled in this area. Computer programs also have been developed to aid the process.
A psychiatric profile (see Chapter 4) often is developed for the missing person before the aging process is applied to the old photograph. A profile provides a look into the type of personality, habits, beliefs, and many other factors the person may have possessed. For example, if a missing person has a social or religious bias against plastic surgery, the artist can reasonably assume that the person didn’t alter her appearance. Likewise, if the victim led a sedentary lifestyle, facial changes from aging would be more pronounced than they would be if the victim had been athletic when last known. In short, the artist uses the information from the psychiatric profile to theorize what facial changes the individual is likely to have experienced through the years.