III. Reading
Choose the best answer 10%
Since the late nineteenth century, fingerprint identification methods have been
used by police agencies around the world to identify suspected criminals as well as
the victims of crime. The basis of the traditional fingerprinting technique is simple.
The skin on the palmar surface of the hands and feet forms ridges, so-called papillary
ridges, in patterns that are unique to each individual and which do not change over
time. Even identical twins (who share their DNA) do not have identical fingerprints. The best way to render latent fingerprints visible, so that they can be photographed,
can be complex and may depend, for example, on the type of surfaces on which they
have been left. It is generally necessary to use a ‘developer’, usually a powder or
chemical reagent, to produce a high degree of visual contrast between the ridge
patterns and the surface on which a fingerprint has been deposited.
Developing agents depend on the presence of organic materials or inorganic
salts for their effectiveness, although the water deposited may also take a key role.
Fingerprints are typically formed from the aqueous-based secretions of the eccrine
glands of the fingers and palms with additional material from sebaceous glands
primarily from the forehead. This latter contamination results from the common
human behaviors of touching the face and hair. The resulting latent fingerprints
consist usually of a substantial proportion of water with small traces of amino acids
and chlorides mixed with a fatty, sebaceous component that contains a number of
fatty acids and triglycerides. Detection of a small proportion of reactive organic
substances such as urea and amino acids is far from easy.
Fingerprints at a crime scene may be detected by simple powders, or by
chemicals applied in situ. More complex techniques, usually involving chemicals, can
be applied in specialist laboratories to appropriate articles removed from a crime
scene. With advances in these more sophisticated techniques, some of the more
advanced crime scene investigation services from around the world were, as of 2010,
reporting that 50% or more of the fingerprints recovered from a crime scene had
been identified as a result of laboratory-based techniques.
Text source:
Fingerprint. (2010, December 19). InWikipedia, The Free Encyclopedia. Retrieved
19:14, December 21, 2010
【題組】32. According to the article, amino acids and chlorides in fingerprints originate from
the
I sebaceous glands
II eccrine glands
III papillary ridges
(A) I only (B) II only (C) III only (D) I and II only (E) none of the above
寫作批改
VIP與詳解卡管理
私人筆記( 0 )
