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inning article of the
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Each
person is unique, evidenced by
the very tips of our fingers. Scientifically known
as epidermal or papillar y ridges, fingerprints
are distinct to every individual. Even identical
twins have different fingerprints! Thus, fingerprint
identification is one of the most fundamental
methods of forensic science, and is recognised as
such - - references to it can be ubiquitously found
in television shows and films. But let’s not take
the science behind this valuable technique for
granted. How does fingerprinting actually work?
Forensic scientists classify fingerprints into three
categories based on the surface upon which it
was left: plastic, patent and latent. Plastic prints
are those of which are left on soft surfaces such
as wax and wet paint, and are often three-
dimensional. Patent prints are clearly visible prints
left on non-porous surfaces, due to the transfer of
blood, dirt, ink or paint from the fingertips to the
surface. Latent prints are the most subtle of prints,
formed due to the deposit of oily residue known
as sebum, which reside on the fingertips. Barely
visible to the naked eye, they can be found on
both porous and non-porous surfaces.
The former two can be easily documented by
photography, but latent prints are more difficult
to obtain. The use of specialised tools is necessary
to increase the print’s visibility. Dusting for prints
with special fingerprint powder is universally
recognised, but there are two other lesser known
methods by which latent fingerprints are captured.
In the United States, the Reflected Ultraviolet
Imaging System (RUVIS) is one such tool commonly
used by law enforcement agenci es . RUVI S
operation occurs in two stages: first, a portable
shor twave ultraviolet (UV) light is shone onto
the non-porous surface, which will either reflect
每
個人都是獨一無二的，證據就你的指尖上。指紋
的學術名稱是乳突線紋，因人而異，即使是同卵雙胞胎的
指紋也是不同的！因此，指紋識別是法證科學必用的方法之
一，在電視劇與電影中也會經常出現相關情節。但是，指紋
是如何收集鑑定的呢？且讓我們看看指尖背後的科學。
法證學家將指紋分為三種：成型紋、明顯紋和潛伏紋。
成型紋是留在軟性材料表面，例
如蠟和未乾油漆上的指紋，往往
保留著三維特徵。明顯紋是清晣
印在無孔表面的指紋，通常是由
沾上血液、污物、油墨或油漆的
指尖留下。潛伏紋是最隱晦的指
紋，由殘存的指尖皮脂所形成，
可以在多孔或無孔的表面找到，
很難用肉眼看見。
成型與明顯指紋很容易被拍照留存，搜集潛伏指紋卻
沒那麼容易，必須使用專門的工具增加指紋的可見度。除了
眾所周知的特製指紋粉，其實還有兩個方法可以套取潛伏
指紋。
美國執法機構通常使用反射式紫外線影像系統
（RUVIS）。RUVIS內置特殊設計的鏡片，可讓紫外線穿透
並阻隔其它波長的光線，增強指紋
影像的清晰度。在具體操作時，先
以便攜式短波紫外線燈照射無孔
表面，光線會被反射或吸收，法證
專家再以手提RUVIS裝置捕捉指
紋影像。
化學顯影劑茚三酮也可用於收
集指紋。除了皮脂，指紋分泌物一
