The following is a description of the process used to identify human remains, principally the process used to identify remains recovered from Southeast Asia. I hope my unscientific explanations provide some helpful information. I believe this information may be of interest because of the continuing return and identification of remains from Southeast Asia. I am not a forensic scientist.
What I know and pass on in this message is information I gained from the people who actually do the work -- the forensic anthropologists, forensic odontologists (forensic dentists), and the equipment recovery specialists who work at the U.S. Army Central Identification Laboratory - Hawaii (CILHI).
For years, the remains that have been returned from SEAsia have been skeletal remains
(no flesh) and, most often, have been only partial remains. "Partial" ranges
from being a few bone fragments up to being a large percentage of a skeleton. Several
aspects of a person can be determined from a skeleton. How much can be determined, and how
accurate the determination is, is determined by which parts of the skeleton you have, the
condition of the remains, and the records available. From a skeleton, a forensic
specialist can determine:
Notice that from a skeleton you do not determine identity. You determine characteristics that lead to identity.
Teeth can be used to determine identity depending on the teeth available to work with and the records available for comparison.
Okay, so how does this work? Here comes a layman's explanation of it.
The eye and nose openings in the skull and certain proportions of the skull vary by racial group between the Mongoloid, Negroid, and Caucasoid races. By examining the skull, or certain parts of the skull, forensic folks can determine the race.
But, what about a GI who was Japanese / Chinese / Vietnamese - American? Would he not show up as Mongoloid? Yes, but, here is an interesting thing I learned at CILHI. A major portion of the diet of SEAsian Mongoloids is indigenous rice, which is harder than our rice. A few years of eating local rice produces wear patterns on the teeth of SEAsian Mongoloids that are markedly different from those on the teeth of, say, a Japanese-American GI who grew up eating our relatively soft diet. So, if there were a few teeth present, especially the grinding teeth (molars), the wear patterns would distinguish an American from SEAsian Mongoloid.
The pelvic structure of women is different from that of men because they give birth and the pelvic bones have to be wide enough to permit that. Plus, women's skeletons are generally smaller in every respect.
Everyone is familiar with the soft spot on a baby's head. The skull is, at birth, soft so the head can squeeze out of the birth canal and the top center of the baby's skull is cartilage, not bone. This cartilage opening closes up as the baby grows and the skull closes over it. Still, on an old adult, there is a visible line down the center of the skull where it grew together.
Did you know that humans have similar soft spots on other bones? Read on.
The long bones of the arm and leg grow in length until you reach roughly your mid-twenties. These bones grow from the ends and there is, on the joint end of each long bone, a fissure similar to the fissure in the top of the skull. As you get older, and bones reach their full growth, the fissure closes.
Forensic scientists have examined thousands of skeletons over the years of people whose age was known. This research has developed a correlation between the degree of closure of the fissure at the growth end of the bone and age. Thus, if you have a leg bone, and if the fissure on the growth end is long and wide, the bone is from a young person; if the fissure is almost completely closed, the bone is from an older person.
Now, I am not sure about this but I believe there is some point -- possibly in the mid-twenties -- where the fissure closes and age can no longer be determined using this method. And, the age determinations that result from this are in a range, plus or minus a few months.
Tall people have long leg and arm bones, short people have short leg and arm bones and people in between have leg and arm bones in between. Again, forensic scientists, from examining thousands of skeletons of people whose height was known, have developed charts that tell you, if these arm and leg bones are this long, then the person was this tall (plus or minus a small amount).
Muscles are attached to bones by ligaments and tendons. When you exercise a muscle, the point where the muscle is attached to the bone is strengthened (and remember, exercise is not defined as pumping iron; a right-handed person exercises his right hand far more than his left). So, by examining these points, the forensic people can tell if a persons muscles were well-exercised, etc. In a case where portions of the hands and forearms are available, an examination of the muscle attachment points can lead to a determination of handedness (the hand that the person used would show much heavier musculature).
Old injuries show up on skeletons, especially broken bones. For example, if you broke your leg playing football, there will be a healing scar on the bone forever. The mark will nearly disappear with age, but it will still be there.
Now, all this is interesting but it does not necessarily lead to a definitive identification of a skeleton. After all, if we determine that this is the skeleton of a Caucasian, between 72 and 74 inches tall, with big muscles, right-handed, between 22 years - 6 months and 23 years old, who at one time had a broken right forearm, we have just described a lot of missing men.
But, what if we recover those remains from a crash site and the aircraft had a crew of two: one was 22 years 9 months old who broke his arm at age 10, and the other was 35 and never broke a bone, then we can make a conclusion: These bones are the younger guy and these bone fragments that we cannot tell much about are the older guy. Things are not always that clean; but, the evidence that can be collected from skeletal remains goes into the whole equation of identification.
Teeth are another matter because of certain characteristics that are unique to individuals. Everyone has a different tooth structure. You may have 29 teeth that are exactly like those of someone else, but there are 3 teeth that are different and the relationship of the 29 that are alike will be different. Unfortunately, it has only been in recent years that we started requiring a full-mouth x-ray of everyone (I think it's called a pantograph x-ray, or something like that).
Previously, the only dental records we had were paper records and partial x-rays. Remember when the dentist looked in your mouth and called out "X number 32, caries on #30 and 28, amalgam filling on 23, etc., etc." and the dental assistant made some marks on a chart? ("Caries" is dentist-speak for decay, a cavity that has not been treated.) That description was translated into pencil marks on a dental chart and everyone's dental chart will be different because no one has exactly the same teeth pattern. X-rays were taken if you had certain work done and rarely were full-mouth x-rays taken so the records could have anything from no x-rays to lots of x-rays.
An important element in using teeth as an identifier is the presence of restorative work -- filling, root canals -- on teeth. When the dentist drills a hole in your tooth to pack in a filling or to do a root canal, each hole is different because the drill will go in an ever so slightly different direction each time. So, if you recover a tooth, and if that tooth has a filling, you place the tooth in an anatomically correct position (stand it up just like it's in the mouth) and x-ray it. Then, compare that x-ray to x-rays of the same tooth of the person who is under consideration. I have seen this done and it is amazing: the x-ray shows an outline of the tooth and the filling and it slides exactly over the x-ray taken from the guy's dental records, and it's a match. Or, it's clear that this does not match, although it may be close.
At CILHI, they have entered into a computer everyone's dental records -- sort of an electronic dental chart. Then, if some teeth are recovered, the forensic odontologist performs what amounts to a dental exam on the teeth. By careful examination, he can determine that he has, for example, eleven teeth, numbers 8, 9, 12, etc. He then enters into the computer "amalgam filling on whatever-position of #8; caries on backside of #9, etc., etc." The computer then compares this description to everyone's dental records and spits out several candidates. One guy's dental records may be an exact match, another matches except that one tooth is different, another may have 75% matches and 25% mismatches, and so on. If there are unique characteristics, such as fillings that match x- rays taken while the guy was still alive, that makes identification easy.
In any case, the whole body of evidence must be reviewed - evidence from the skeleton, evidence from the teeth, and evidence from the recovery -- before an identification is made.
Evidence From the Recovery
Sometimes the circumstances of where and how the remains are recovered are critical, even conclusive. A relatively easy case would be that of a single-seater aircraft that was seen to go into the ground. Excavation of the crash site finds bone fragments, a couple of teeth, a boot heel on which you can read the size, some eyelets from the boots, a belt buckle, a watch, and several parts of the ejection system. These findings, especially the presence of parts of the ejection system, show that he did not get out of the aircraft. Thus, because we know which aircraft was excavated (serial numbers from pieces of wreckage are compared to serial numbers in logistic records), and we know who was in it, and we find that he did not get out, then we can conclude that these fragmentary remains are this man.
Why fragmentary remains? Why not big parts of a skeleton, especially the large bones of the body?
Several years ago, in the early days of operational status for the B-1, a B-1 with a crew of four went into a hillside in Texas. Search crews were on the scene within a few hours. They recovered two badly mangled but identifiable bodies and eight pounds (I believe it was) of miscellaneous human flesh. Using blood typing and nuclear DNA matching, the flesh was separated into two people, who were identified by blood type and DNA. But, what if it had taken 25 years for the search crews to find the crash site? What would they have found, given the action of wild animals, rain, sun, acidic soil, possible scavenging of the crash site, and so forth?
In many cases, it's a wonder that bone fragments remain.
This is an important point: What happens to the body in a high-speed (and, sometime, a not-so-high-speed) crash? I forget what the statistics are, but the USAF once told us what percentage of people they are able to identify from peacetime crashes where search and recovery personnel get to the crash immediately -- the number is small because bodies are shredded from the force of the impact and are destroyed in fires.
So, we are back to the point that a crash tends to destroy the body and, when whatever is left is subjected to natural deterioration and climatic conditions for years and years, there often is not much to recover.
I have given the example of a single-seater. What about the excavation of the crash site where there were 10 members of the crew? or 8 guys on a Huey? or a grave site with three guys in it? It all depends. In these cases, especially aircraft crashes, it may not be possible to identify everyone individually. So, they look for: Where were bone fragments found , at or near which crew position(s)? What else was found such as personal gear that would have been with the guy (pistol, rings, watch, religious medallions, other unique stuff)? Parachute rings still in the wreckage? What did eyewitnesses report? What did wartime search and rescue efforts turn up?
It is not simple and each case is different. Throughout, however, you have to apply both scientific method and logic.
Until a few years ago, the only identification process available was to consider the body of evidence gathered from the skeleton, the teeth, and the circumstances, then make a conclusion. Now, however, DNA matching provides positive identification much more readily (usually).
I am not a geneticist so I don't know all this scientific stuff but the folks at the AFDIL (Armed Forces DNA Identification Laboratory) led me through it one day. Here goes my unscientific explanation. DNA is a molecular structure that carries the genetic material that defines who we are. Certain parts of the DNA molecule control various thing such as hair and eye color, sex, tendency to obesity, and the millions of other characteristics that make each of us unique. Thus, each person's DNA is unique. There are, however, certain DNA characteristics that are inherited. Thus, a DNA sample from a parent will have a lot in common with a DNA sample from that parent's child but will have nothing in common with anyone else.
Complicating matters are the fact that there are two types of DNA: nuclear DNA and mitochondrial DNA (mtDNA). Nuclear DNA is in the nucleus of the cell and it decays as the flesh decays. MtDNA is in the mitochondria, or the wall, of the cell. It survives for a long time and can be recovered from bones.
And, here is an important point: mtDNA is transmitted through the maternal line. Thus, your mtDNA will match that of your mother and grandmother but not of your father. Your children's mtDNA will match their mother and her mother, not your and your mother. (I am not certain about nuclear DNA.) MtDNA testing is destructive. You have to cut off a small piece of the bone and treat it with chemicals, basically dissolving it in the process.
MtDNA may or may not be recovered from a bone depending on the size of the sample, what environmental degradation it has been subjected to, etc. The technology is improving all the time and the ability to recover mtDNA is improving.
Families of missing men can submit a blood and saliva sample to AFDIL. (The family contacts their service casualty officer who sends them a sample kit and they go to their own physician to collect it.) AFDIL will then map the DNA from the sample and catalog it. Then, if bone fragments are recovered, and mtDNA can be recovered from the fragments, identification is a process of matching.
Here is a chart showing how mtDNA is passed through the maternal side of a family. In the center of the chart is the missing individual -- those persons highlighted in the chart could provide mtDNA for matching purposes.
In addition to the link to the AFDIL web site (above), here is a link to the DPMO web site article on mtDNA testing.
ADDENDUM. The following paragraphs -- indented to distinguish them -- were added on January 2, 1999.
End of January 2, 1999 addendum.
The Identification Process
Okay, so all the research has been done -- examination of skeleton and teeth, circumstances of recovery, and, if possible, DNA matching. Now what? Does some clerk just declare that these remains are this guy, so send his saddle home? Not at all. There is a long approval process.
First, is peer review. The scientists and recovery specialists at the CILHI must present their findings to others at CILHI who read the reports, review the work, hear their briefing, then approve what was done, or send it back for rework.
Once CILHI sends forward a recommended ID, the Army (who has DoD responsibility for identifications) contacts three consultants. These are forensic scientists throughout the country, at universities or research institutes. The Army maintains a number of these individuals under contract. The reports of the lab work are sent to three of the consultants who review CILHI's work. These folks can: agree with CILHI; ask for a clarification and talk with CILHI; or, go to CILHI to do some work themselves.
Eventually, assuming they are satisfied, these consultants add their recommendations to the CILHI recommendation. The whole package then goes to a board of officers, normally colonels, chosen at random who provide the "reasonable man" check. They review the whole report and can do anything they want to with it -- approve, disapprove, ask questions, send it back.
After board approval, the recommendation goes to the service secretary (that is, Secretary of the Army, navy, or Air Force) for final approval. With service approval, the whole package goes to the family.
A casualty officer explains the identification process and findings to the family -- who normally has been told of things as they go along, anyway.
Note: Throughout this article and the MIA Facts Site, I use the term "family." Who is "Family?" For a missing man, the one family member whose word is final is the Primary Next Of Kin -- the PNOK. PNOK is established by law and can be changed by designation by the PNOK.
The family can then: (1) accept the identification; (2) ask for an outside opinion; or (3) reject the identification. If the family accepts the identification, the remains are released to them for burial. If the family asks for an outside opinion, CILHI will transport the remains to the location of the family's expert, or, make the remains available to the expert at CILHI. If the family's scientist/expert disputes the findings, then a process of review starts. I do not recall all the possible permutations of this process.
If the family rejects, then any number of things can happen. By law, the service secretary can order that the remains be interred because, by law, DoD has identified the man. That would not be the best way to treat a family. In fact, if the family rejects, then a process of review starts up.
Again, this could go all over the place, depending on any number of circumstances.
Caution: When I left DoD in March 1995, there was a proposal going around that would have modified the identification approval process. I was gone by the time the proposal got up to SECDEF so the process may have changed a bit from what I described but, in the main, that's the way it works. Hope this has been helpful and informative.
Here are links to four must-see sites.