Quality Standards for Forensic Opinions on the
Identity of Living Offenders In Pictures
F. W. Rösing
Institut für Humangenetik und Anthropologie Universitatsklinikum
The forensic identification of persons
in photographic documents follows established scientific criteria and
methods. The recognition of human faces, however, is a highly developed,
natural human skill. The widespread belief that a professional forensic
identification is as easily accomplished as common facial recognition among
individuals is problematic. In response to the problems generated by this
mistaken belief, a group of university-based experts has formulated a set of
quality criteria for such identification opinions. The goal of these
criteria is the creation of an identification system that can be
peer-reviewed for expertise. The criteria are as follows:
The main principle of photographic
identification is the assessment of detailed structures in a slow and
thorough process and with a gradation of the result, as opposed to
holistic, fast, and polarizing daily recognition.
The country-specific judicial basis
must be considered.
Photographic cameras are recommended
for surveillance equipment as video cameras have too low a resolution. A
surveillance camera should not be installed too high above the scene
because this reduces recognition of the lower face. For an identification,
comparison pictures of the suspect should be made, preferably with the
original security camera. An identification should be performed by
picture-to-picture comparison and not by a picture-to-person comparison.
The picture quality influences
recognition. This is an independent variable that must be assessed in
every extracted trait parallel to the assessment of the trait itself.
Identifying traits are morphological
structures that can be seen on the surveillance picture, particularly
those of the face and ears, but also of the thorax or hands, or of stature
and posture. Population frequencies are decisive in the assessment of
traits, and the possibility of a secondary change of traits (e.g., through
use of a mask or other means of obfuscation) should be considered.
The expert opinion may explain the
scientific bases of photographic identification. All traits found must be
described, preferably using established anthropological nomenclature, but
with due regard that the opinion should be understood by non-experts.
Partial expert commissions—for example, of an ear-should not be accepted.
All principles used and assumptions made must be described through every
step of the identification process. The result of an expert opinion is the
The identity probability depends upon
the number and rarity of the traits found. If traits are independent from
each other, the single probabilities are multiplied according to the usual
probabilistic rules; if the traits are correlated, the covariance reduces
probability. If trait frequencies are not formally known, they should be
estimated. For the final probability result, a verbal formulation should
be given, possibly also a figure, together with the range.
The principle of preselection must be
considered. The normal probability assessment depends upon the assumption
that a suspect is a chance draw from the general population. If he or she
has been found using the surveillance photograph, this is not a chance
draw. Then every suspect named is similar to the offender. Consequently,
the population-based probability assessment can not be applied, but the
demands for rarity of traits increases, and traits that are normally not
included in the recognition of persons, such as the ear traits, become
As a general precaution, the
possibility that a close genetic relative might also be suspected should
be checked. He or she should be included in the identification process.
The scientific basis of photographic
identification is physical anthropology, which includes as a subfield the
morphology of living persons. The assessment of external traits formerly
used to diagnose paternity is particularly useful as a basis. A medical
doctor or criminalist might acquire and develop the necessary knowledge
and experience of physical anthropology during work on scene or in the
Several procedural steps are recommended
for quality assurance, including regular determination of the intra- and
inter-observer error, the exchange of model cases, consultation with
colleagues before opinions are issued, and the examination of new members.
Buhmann, D., Helmer, R. P., Jaeger, U.,
Jürgens, H. W., Knussmann, R., Rösing, F. W., Schmidt, H.D., Szilvássy, J.,
and Ziegelmayer, G. Standards für die anthropologische Identifikation
lebeder Personen auf Grund von Bilddokumenten. Grundlagen, Kriterien und
Verfahrensregeln für Gutachten, Anthrop Anz (1999)
57(2):185–191. (Also published in Dt. Autorecht [April 1999], pp.
188–189; Kriminalistik [April 1999], pp. 246–248; Neue Z.
Strafrecht NStZ  5:230–232; Rechtsmed  9:152–154.)