In 2002, skeletal remains were found in Boulder County Colorado. Initial characterization of those remains was consistent with a young adult male, perhaps 17-20 years old at the time of death. Those remains have recently been identified by DNA testing as Cristobal James Flores (Longmont Colo Times-Call March 26, 2014)
Young Mr. Flores had gone missing from his family's home in Aurora (eastern suburban Denver area) way back in September 2001. There is not a lot of information about his disappearance, but his curious "reappearance" thirteen years later via DNA has some interesting aspects.
How do investigators identify a particular set of remains as being a particular individual? This field is sort of a merger between pathology and anthropology, under the rubric of forensics. I would say that the distinction between a forensic pathologist and a forensic anthropologist is mainly a matter of how long the victim has been dead.
Here is a nice elementary review related to identification of MIAs from the Vietnam War. Here is an example of the steps taken to identify remains in a general investigation.
So what can we determine about a set of skeletal remains?
Skeletal remains can range from a single small bone fragment to nearly complete skeletons. Initial forensic analysis focuses on identifying the remains as human or non-human. The more complete the remains, the easier it is to make this distinction. Even with single bones however, both macroscopic and microscopic features can be analyzed to make this determination. Although other large mammals such as elk or bear can have bones that are similar in size to a human, generally a determination can be made with confidence.
Here are some of the features used for macroscopic (anatomic) determination:
and here is an abstract link to a publication describing microscopic (histologic) determination.
The location where skeletal remains were found can be used to help make an identification, in a general sense. Obviously, the likelihood of skeletal remains found relatively close to the last known location of the missing person will have a higher likelihood of being that person than remains found halfway around the world. Equally obviously, this does not prove identity. Items found in the vicinity of the remains (clothing, personal items, etc) can also give clues to the identity.
3. INDIVIDUAL CHARACTERISTICS:
-AGE (at the time of death)
-IDENTIFIABLE INJURIES OR PATHOLOGIES
While determination of individual characteristics does not allow specific identification of an individual, it can allow the forensic investigator to narrow the possibilities. If your missing elderly Aunt Edna was not 6'3" tall and male, she can be eliminated from consideration when the discovered remains have those characteristics.
4. SPECIFIC INDIVIDUAL IDENTIFICATION:
There are two main techniques utilized by forensic investigators to confirm an individual identity, dental comparison and DNA profiling. Both of these techniques require an unknown sample to be matched with a known sample. In the case of dental records, this control sample is usually written dental records and previous X-rays, that can then be matched to specific findings in the teeth of the unidentified remains.
In the case of DNA testing, the control sample can be from the personal effects of the missing person (hair from a hairbrush, dried saliva from a toothbrush, etc.) or from first-degree blood relatives (parents, siblings, offspring).
I will talk more about DNA testing on a future post.