148 Forensic dentistrythose things. When individual identifiers are available, those with a known
incidence can be entered into the calculation, reducing the set of possible
matches toward unity. Identifiers that can be traced directly to a decedent
provide the basis for a positive identification, e.g., an intramedullary rod
or a pacemaker with a serial number that matches a surgeon’s record for a
particular patient. In such instances it is imperative that direct association
between the decedent and the device can be established. For example, an
orthodontic or orthopedic device affixed to the remains is preferable to
one that has become detached. Experience in mass death incidents involv-
ing scattered and commingled remains bear this out. In some instances an
implant, orthopedic device, or prosthesis may be found in a decedent without
a suspected match. If the medical artifact bears a serial number and can be
attributed to a particular manufacturer, it is sometimes possible to trace the
device to a particular treatment facility, and thence through surgical records
to a recipient. Whatever the means of identification, in the post-Daubert era,
all conclusions and the techniques from which they are derived will require
robust statistical support. As an example, though used as a basis for positive
identification for years, comparison of ante- and postmortem frontal sinus
x-rays has only recently been validated.^51 When unknown remains come to
light for which there is no suspected match, the only remaining course of
action is submission of the osteological and odontological findings to the
appropriate database (see below).
8.2.6 Postmortem Interval
Forensic anthropologists are sometimes asked to estimate the postmortem
interval (time since death) for a set of remains. The main reasons for esti-
mating the postmortem interval are (1) the inclusion or exclusion of suspects,
(2) reduction of the number of possible matches in a database, and (3) deter-
mination of the forensic significance of a set of remains, i.e., is the decedent
an archaeological or historical specimen, or a contemporary case that requires
investigation? On most occasions, when an anthropologist is asked to deter-
mine the postmortem interval, the decedent will have been dead for weeks to
years. Ideally, the remains will be pristine, and it is for this reason that many
examiners prefer to attend the recovery, whether it may be an exhumation,
collection of scattered bones, or even submerged remains. The anthropolo-
gist may supervise and document the process, collecting relevant samples,
e.g., insects, botanical specimens, clothing, coins, or other “time givers,”
which will be transmitted to appropriate specialists for further analysis. But,
most importantly, he or she will want to assess the remains in context before
any processing occurs. General observations will include corporal (from the
body) as well as environmental information: What is the quantity and qual-
ity of the remains? Do the remains express any odor? To what extent are the