This call comes in to almost all police departments at some time: "I stumbled across some bones. I think you might want to check it out."
The officer dispatched to the scene should assume the bones are human, there are more bodies buried, and should collect evidence accordingly.
But unless the officer is an expert in human osteology, he must be very careful how the bones are handled. If there is no danger of damage from the environment, the officer should leave everything intact and call in a forensic recovery expert.
What the officer should do is immediately set up a perimeter. Though the area within that perimeter may be completely wrong — if the area turns out to be a multiple body dump site — at least there is a starting point. An agency should also post a guard at the site until forensic recovery experts arrive.
Though not directly involved in the recovery effort, however, it is imperative that all officers have a basic understanding of bone collection and what types of information can be gleaned from them bones.Documentation and removal
Every scene involves different circumstances and requires modified approaches of documentation and removal, note Tim White and Pieter Arend Folkens in The Human Bone Manual. The authors point out remains may be located in a number of ways, including mechanical means, such as remote sensing, sonar, radar, heat sensing and aerial photography; or via physical efforts, such as the use of scent dogs, divers or search and rescue teams.
Once the skeletal remains are found, recovery experts must determine whether the bones are scattered across the surface or buried in a relatively intact state.
Scattered surface remains can be documented as a sketch using stationary objects as landmarks or, if in a relatively small area, a grid can be created with string, according to Foothills Search and Rescue (SAR) society in Alberta, Canada. Foothills SAR reports that scattered surface remains can be marked with flags or other visible markers and added to the sketch or grid before removal.
Buried remains require a different collection procedure. The same grid is used but bone removal becomes more complicated. The recovery specialist removes earth around the burial with a series of shovels and trowels in descending size as he or she nears the actual bones. Brushes are used in the final stages of exposing the remains. The examiner then photographs the bones with an indicator of size and orientation in the picture.
Next, the removal process proceeds in two ways. The bones can be removed one by one and packaged separately with labeling indicating the type of bone and the side of the body it came from. But if an inspection of the pelvic region indicates the presence of fetal remains, or if the bones appear to be from a child, then another method should be employed. Juvenile and fetal remains contain many tiny bones that have not yet fused with others and are easily lost in the soil. Here, it is advisable to utilize a method employed by paleontologists to remove fragile dinosaur bones. In this process, White and Folken explain the bones are exposed, then a pedestal of earth is made by excavating around them. Wet paper towel is draped over the remains, which are then wrapped in burlap. Later the bones are coated in plaster. As the plaster dries, the remaining bottom sections are encased and the entire burial is transported to the lab as a whole. Even when using the paleontologist method, the surrounding area should be processed using a series of ever-diminishing screen sizes to check for small bones and other evidence such as vestiges of clothing.Are the bones human?
A forensic osteologist can examine recovered bones for clues to determine if the remains are human; how long the person has been dead; the victim's age, sex, height, racial affiliation, and more.
One of the first things established is whether or not the bones are human. If there are intact long bones or a skull, this finding can be fairly straight forward. If the bones are fragmented, however, it becomes more difficult to judge. Human bones vary significantly in both size and shape. Bear paws are often mistaken for human feet. Pet rabbits and guinea pigs are also mistaken for human fetal remains.How long have the bones been buried?
If the osteologist determines the remains are human, the next question to answer is antiquity of the burial. Generally in forensic investigations, 50-75 years antiquity is the cut-off time, according to Forensic Pathology: Principles and Practices by David Dolinak, Evan Matshes and Emma Lew. Forensic investigations focus on solving a crime. If the burial occurred more than 50-75 years ago, it is unlikely a criminal prosecution will occur. But the missing individual's relatives will still want to know if the remains belong to their loved one.
Antiquity can be difficult to establish. It often depends on the retrieval of non-biological artifacts such as clothing, buttons, dental implants or work, and medical implants or procedures. Each of these items can usually be assigned a manufacture date or a time period in which they were used. Museum curators and other staff can help identify the ages of various objects.How many bones should we look for?
Another common question is: "How many bones are we looking for?" There is no correct answer because unless officials know the victim's age, they will not know the number of bones they seek. The British Broadcasting Corp.'s (BBC's) Science and Nature Web site reports that a fetus has somewhere between 275 and 300 bones, a baby or infant has 275 or less depending on age, and an adult human has 206 bones.How old was the person?
Age can be determined by looking at the growth plate, also known as the epiphysis or epiphyseal plate, found at the end of many bones. As a person ages these plates ossify and fuse to adjoining bone, a process that occurs at a fairly predictable rate. Most bones fuse by the time a person reaches 25, after which time the bones begin losing density and show wear patterns.
In adults, the pelvis and skull can help estimate age. The shape of the ends of the ribs and the pubic symphysis also may aid these estimates. In youth, the pubic symphysis appears rippled. As a person ages it becomes increasingly smooth; by age 50 the ripples have generally disappeared. The degree of rippling is rated using the Todd Method's 1-10 scoring system.
The skull also can indicate age because the sutures that join its bones fuse at a known rate according to age. Keep in mind that there is always a margin of error — maturation differs from individual to individual. In addition, sex, genetic predisposition, nutrition and disease also can affect this rate.
Some sources suggest measuring a skeleton's long bones can also help calculate age. But while long bone measures are fairly accurate in the skeletons of fetuses and young children, after age 4 or 5 this accuracy diminishes.
Examining dentition is the most accurate method of age determination because teeth erupt at a fairly standard rate. At birth the margin of error is +/- two months. By the age of 15, the margin of error increases to +/- three years. Again variable maturity rates between the sexes can create significant error. It is advisable when examining children's remains to determine the person's sex first.What sex was the victim?
Determining sex in adult skeletal remains is said to be one of the easier tasks asked of the osteologist. When the hip bones, skull or an entire skeleton are present, some researchers place the accuracy at 95 percent. When only the skull is found, accuracy drops a bit but still stands at 80-92 percent. Even without the skull and hip bones, it is possible to determine sex given the differences in female and male knee joints, report Dolinak, Matshes and Lew. In general, males have more robust bones and more prominent muscle attachments.
However, despite these differences in stature, the female sacrum (tailbone area) is wider and oval in shape for childbirth. In women who have had children, there is a pitting or rippling on the pubis surface. Known as dorsal pitting, the rippling tells the examiner the remains are from a female of childbearing age. However, this feature does not indicate the number of children the woman has had, and Dolinak, Matshes and Lew speculate that some dorsal pitting may be caused by increases in weight not childbirth.
The next most reliable method is to examine the skull's features. In general the female skull exhibits smoother more rounded features and is somewhat smaller. A male's skull typically has a bony ridge that runs across the brow just above the eye sockets. This feature can be quite pronounced or barely visible. In males, the lower jaw bone is squarer and the ends of the lower jaw where it attaches to the upper portion of the skull span a wider distance. The male jaw bone projects outward, while a female's slopes back slightly. If a skull's eye socket surface is rough it is female; if it is smooth it is male. On the back of the male skull, there is a protrusion that makes the skull appear rounded. Female skulls have a flattened area that starts at the crown and extends about half way down the back of the skull.What is the victim's race?
A forensic examiner also may be asked to predict the racial affiliation of the remains.
Three main categories are used to define racial affiliation: Caucasian (white), Negroid (black) and Mongoloid (includes Asian, Native American, Hispanic, some Middle Eastern and some Eastern European). Imagine a skull viewed from the side, then imagine a vertical line that starts at the forehead and runs straight down toward the chin. This is known as the vertical plane of the face. From this area, it is possible to guess the race of the human skeleton. Donilak, Matshes and Lew report the differences between the three as follows:
- Caucasian. The nasal bone extends perpendicular to the vertical plane. The top of the nasal opening has a pinched appearance. At the base of the nasal opening there is what is called a "nasal spine," which protrudes outward from the vertical plane. The upper margins of the eye socket may appear to slope away from the nasal opening. The eye socket appears to recede from the vertical plane. The lower jaw bones (not the teeth) have a square appearance. The palate is generally "V" shaped. The muscle attachment sites on the skull are more pronounced in Caucasians than in the other races. The sutures are straighter than in Negroid or Mongoloid skulls.
- Mongoloid. The nasal root slopes back into the nasal opening. The facial bones tend to be oriented along the vertical plane. The nasal opening is generally wider than in Caucasians. The upper margins of the eye socket (orbital opening) can either appear round or square but do not slope downward. The zygomatic arches or cheek bones are prominent. The incisor teeth tend to be fairly thick. The back surface of the teeth may have prominent depressions, giving them a spoon shape. The sutures are generally more complex than in Caucasians. The palate is a half-circle shape.
- Negroid. The upper and lower jaws project outward from the vertical plane. The nasal opening lacks the pinched upper portion typical in Caucasians but is not as rounded as in Mongoloids. There is a prominent nasal gutter, which is the depression below the nasal opening. The nasal opening is square. The cheek bones tend to slope back from the vertical plane giving them a sunken appearance. The palate is rectangular in shape. The sutures of the skull tend to be less complex than in Mongoloids but not as straight as in Caucasians.
A forensic osteologist also may determine whether there has been any damage, both before and after death, to the bones. Approximately 80-90 percent of skeletal remains will show evidence of trauma, infection or arthritis, reports anthropologist Sherry Ortner.
Signs of infectious disease can help determine the area of the world from which the person came, and his or her general health at the time of death. For instance, remains that show an old healed ossification due to a disease such as leprosy can indicate the victim originated from parts of the world where the affliction is common. If the damage to the bone is severe, it can indicate that in life, the person walked with a limp or was disfigured in some way.
Trauma to bone can happen in many ways, report Donilak, Matshes and Lew. Fractures are common and can occur either through stress, blunt force or sharp force. Ortner reports stress fractures can be from weight or torsion; blunt force injuries take place when the bone is struck with enough force to break it, such as a car accident or a strike from a baseball bat or other weapon; and sharp force fractures occur when the bone is pierced with a bullet, knife or other sharp object.
The most common question is whether the fracture occurred before or after death. Ortner reports damaged or broken bones show signs of healing about a week after injury. If healing has begun or has already taken place, the injury did not occur at the time of death. A lack of healing indicates the injury occurred less than a week before death, and unhealed fractures of the arms and wrists may be defense wounds.
When the call comes in about a heap of bones, officers need not grab a body bag and throw them in. They simply need to pick up the phone and call in a forensic recovery specialist, who can examine them bones for the clues they contain.
Kathy Steck-Flynn teaches forensic evidence seminars for various groups. She can be reached at firstname.lastname@example.org.