This week, instead of a foray into the wild we attended a lecture, one of the most fascinating I have ever heard. For a start, it was held in the US Armed Forces Institute of Pathology, so there were lots of flags, pictures of people in uniform and officialdom. The lecturer, Dr. William Rodriguez, (real name) started out as a primatologist in Africa, then moved to working with odors – how animals interpret smells. He also worked on war crimes in Kosovo, Somalia and Iraq, so an impressive resume.
It turns out that odor was first used to diagnose crime in 13th century China, where flies were used to discover a murder weapon. Even though the weapon had been wiped clean, the flies could still smell the traces of blood.
We were informed that certain animals can cause injuries which look like weapon injuries. For instance, there is a mollusk which makes perfectly round holes in skulls which looks like a gunshot entry wound. Then there are snapping turtles which can crush the frontal skull which makes it looks as if the person was bludgeoned to death. When dogs try to pick up skulls they typically try to pick it up from the back and leave striations which look like knife marks. To carry the skull they have to pick it up from the front which tends to fracture it.
The lecture continued with stories about decomposition. Its predictable sequence leads to visible (to those in the know) bio-environmental evidence. A dead body disrupts the ecology of the area, as it is a food source for animals and plants. When a body is buried, it first bloats up. As the body off-gases, the area directly above the grave caves in and the surrounding area cracks somewhat. Often vegetation nearby will die-off, since roots may have been cut while digging the grave. When burying a body, it is difficult to avoid mixing the soil around, and under-soil gets dumped on top on the body. In this case, a bare patch may be a tell-tale sign, since seedlings will not grow so well on soil devoid of nutrients. When soil is dug up it becomes more porous and water accumulates there better than surrounding areas, so the area will be darker. Also, different types of plants grow, often those with dark green leaves which favor the liquids from decomposing bodies. This can be very obvious if a body has been buried in a field or agricultural area, and the difference in color can be seen from the air.
Plants and insects can often help determine when the body was buried: when seeds start to grow in disturbed ground, forensic ecologists can tell by looking at the plant how long it has been growing. Our lecturer said that this, and other, evidence was destroyed by the DC police in the case of Chandra Levy. He and his team went to the area when they heard a skull had been discovered. The DC police department used leaf-blowers and threw soil down a hill, destroying all of the ecological and biological evidence. Soon after they released the crime scene and all manner of people, reporters and private investigators, crawled all over the area. One of the private investigators hired by the family found a leg bone, so once again, the police sealed off the area. They never found her hair, but Dr. Rodriguez said if you know where to look, hair can often be found.
Many little critters like using hair as nesting material, both birds and rodents, and nests are often close to the site, in nearby trees either in the branches, for birds’ nests, or near the base of the tree for rodents. They also find teeth and small bones. In one case there was a wedding ring in a field mouse’s nest. In another amazing case, a yellow warbler had plucked not only hair from the skull of a victim, but had a little piece of paper built into the nest. This piece of paper had a telephone number on it, which turned out to be the phone number of the murderer!
If a skull and a body have been separated, it is possible to tell which way up the face was, by “soil stain” on the bones. One can even tell if the skull has been moved several times. The bone which is least often recovered is that of the hyoid bone, and this is unfortunate because it is a clear indicator in the case of strangulation. It is often eaten by buzzards or vultures. Which brings us to another useful tool in toolbox: poop. Dr. Rodriguez collects all fecal samples nearby then x-rays them. Quite often there will be not only bone shards, but also bullet shards.
Wild canids (foxes, cayotes) usually eat close to the death site, therefore bones, and the bones in the poop, are nearby. However, domestic dogs will carry bones long distances, so investigators will go to nearby homes with dogs and look in the yard and kennels – not infrequently they have found human skulls in dog-houses.
When the death occurs in winter, the graves are often extremely shallow, since it is difficult to dig through the frozen ground. The human killers will often mark the area of the burial with pieces of fallen wood, so that they can find it more easily in the spring, when they intend coming back to bury it deeper. Frequently, killers who leave their victims in the woods know the area very well.
Another sign suggesting something is not normal is when the wrong plants are growing in a particular area. What happens is that as a body is dragged from a car at the side of a road to a denser area of undergrowth it picks up seeds on the clothing. These seeds often germinate in spring. Now, roadside plants and trees are different from those found in the woods, and those in the know recognize plants growing in the wrong places. In one case they found a buried body because tulip poplar seedlings were growing in a pine and oak forest.
When the body has been un-earthed by investigators, a variety of insect and plant s give clues to the season of death. Even if a body is 12-15 years old, season of death can be found by looking at insect bodies in bone crevices. For instance, if a very thin yellow jacket is found, it is likely that the death occurred in September or October, because that is when the nest breaks up and when they are actively foraging for anything they can get. There is a branch of this science called forensic entomotoxicology where insects are analyzed to see what chemicals they contain. They can identify opiates and antibiotics, which can give useful clues to cause of death.
For very recent victims, time of death is an important detail. Generally fly larvae (maggots) are a good indicator, but not always. In certain areas ants will carry off the maggots and this slows decomposition, so that even though a body may look 24 hours old, it can be 48. Another factor which alters apparent time of death is the size of the body. Small bodies mummify quite quickly which impairs the insect’s ability to feed. Scarab beetles are the last to benefit from the death. They feed on vertebrate and invertebrate carrion – so often they are eating the dead insects which have eaten the dead person.
We will finish with odor, which is where this started. That is what the dogs are used for, since their sense of smell is prodigious. There are 24 main components of odor of human decomposition. Currently a machine is being developed to detect these odors, but it involves a thin probe which has to be put into the ground at small intervals. That is only useful if you know where the body is, so really, it is not useful at all, compared with a dog. Sometimes a dog indicates an area where there is absolutely no trace of a body, but that is usually because there are some plants which give off exactly the same odors. So, don’t blame the dog!
No comments:
Post a Comment