How reliable is fingerprint evidence? - Theodore E. Yeshion

翻译人员: Angel Y 校对人员: Austin xiao

On October 17th, 1902, Paris detectives arrived at a grisly scene.

1902 年 10月 17日， 巴黎侦探到达了一个可怕的场面。

Joseph Reibel had been murdered at his workplace.

约瑟夫·雷贝尔在他的工作场所被谋杀。

With no eyewitnesses, the officers had little to work from,

由于没有目击者，警官们几乎没有什么可做的，

until they discovered a shard of broken glass

直到他们发现了一块碎玻璃碎片，上面

with several bloody fingerprints.

有几个血腥的指纹。

An investigator manually searched the police station's fingerprint records

一名调查人员手动搜索了警察局的指纹记录，

and eventually found a match.

最终找到了匹配的记录。

Henri Scheffer, who had been arrested for theft the year before,

前一年因盗窃被捕的亨利·舍弗被拘留，

was detained and later confessed to the murder.

后来承认了这起谋杀案。

This marked the first time in Europe

这标志着欧洲调查人员

that investigators solved a crime using fingerprints alone.

首次仅使用指纹侦破犯罪。

Over a century later,

一个多世纪后，

fingerprints remain one of the most common types of evidence

指纹仍然是刑事法庭中最常见的证据

in criminal courts.

类型之一。

But just how reliable are they?

但是它们到底有多可靠？

Humans, like other climbing species,

像其他攀岩物种一样，

are born with patterns of raised ridges and recessed furrows

人类出生时不仅手指上有

not only on their fingers but also along their hands and feet.

隆起的山脊和凹槽的图案，手脚上也有。

These friction ridges help provide a firmer grip,

这些摩擦脊有助于提供更牢固的抓地力，

especially on wet surfaces, and increase our sensitivity to touch.

尤其是在潮湿的表面上， 并提高我们对触觉的敏感度。

They begin to develop in the womb at about seven weeks,

它们在袋熊中开始发育，大约七周后，

when the skin on the hands and feet swell to form smooth raised pads.

手和脚上的皮肤会膨胀，形成光滑的凸起垫。

At around ten weeks, deeper layers begin to grow faster than the upper layers,

大约十周后，深层开始比上层生长得更快，

causing the pads to buckle and fold.

导致垫子弯曲和折叠。

This folding is guided by genetics and environmental factors

这种折叠受遗传学和环境因素的指导，

and continues over the next several months.

并将持续到接下来的几个月。

Scientists have yet to fully understand the exact environmental factors at play,

科学家们尚未完全了解起作用的确切环境因素，

but it’s their randomness that leads to the formation

但正是它们的随机性导致了

of unique fingerprint patterns.

独特的指纹图案的形成。

In fact, many experts believe it’s improbable that any two fingerprints,

实际上，许多专家认为，任何两个指纹，无论是

past or present, are exactly alike.

过去还是现在，都不可能完全相同。

They're even different among identical twins.

在同卵双胞胎中，它们甚至有所不同。

People have likely known about the individual nature of fingerprints

人们可能已经知道指 纹的个体性质已有几个世纪了，

for centuries,

但是直到

but it wasn’t until the late 1800s that scientists began studying and classifying

1800 年代末，科学家才开始研究和分类

their different features.

指纹的不同特征。

By the early 1900s, prosecutors began utilizing fingerprints in courts,

到20世纪初，检察官开始在法庭上使用指纹，

forever changing how detectives approach and analyze crime scenes.

永远改变了侦探接近和分析犯罪现场的方式。

Today, investigators often begin by searching for visible prints.

如今，调查人员通常从寻找可见的指纹开始。

These include patent prints,

其中包括由血液或

left by transferable substances like blood or dirt,

污垢等可转移物质留下的专利版画，

and plastic prints, which are impressions in soft, malleable materials,

以及塑料版画，后者是用柔软的、 可延展的材料（例如填缝剂、

like caulking, wax, or even a newly painted fence.

蜡甚至是新粉刷的围栏）留下的印象。

However, most fingerprints aren't visible to the naked eye.

但是，大多数指纹是肉眼看不见的。

These are called latent prints,

它们被称为潜伏印记，

and they’re composed of the water, oils, proteins, and salts

它们由山脊图案留在表面上的水、油、

that ridge patterns leave on surfaces.

蛋白质和盐组成。

They can be revealed by dusting with a fine powder,

用细粉末喷洒即可露出它们，

which sticks to the water and oil trail.

这种粉末会粘在水和油的痕迹上。

If surfaces are porous or difficult to dust,

如果表面多孔或难以除尘，研究人员

investigators use chemical developers like Ninhydrin,

会使用诸如 Ninhydrin 之类的化学显影剂，

which reacts with proteins left by fingers.

它会与手指留下的蛋白质发生反应。

Forensic scientists continue to develop more sensitive and surface-specific tools.

法医科学家继续开发更灵敏 和更具表面特异性的工具。

For example, one experimental technique uses an electrical charge

例如，一种实验技术使用电荷

to capture the corrosion that fingerprint salts leave on metals,

来捕获指纹盐在金属上留下的腐蚀，

even if they have been wiped down.

即使它们已被擦掉。

Once investigators have collected prints,

一旦调查人员收集了指纹，他们就会

then they get to work matching them with potential suspects.

着手将它们与潜在的嫌疑人进行配对。

In certain cases, investigators will use automated computing systems

在某些情况下，调查人员 将使用自动计算系统来缩小国家

that can narrow down potential matches

指纹数据库中可能

found in national fingerprint databases.

存在的匹配范围。

Certified experts then compare minor fingerprint details,

然后，认证专家比较细微的指纹细节，

such as how the ridges branch and intersect,

例如山脊的分支和交叉

and the spacing of oil pores.

方式以及油孔的间距。

Any result must be blindly verified by a second expert

在将信息移交给司法部门

before information is handed over to justice departments.

之前，任何结果都必须由第二位专家盲目验证。

The fact that fingerprint patterns are unique for every individual

每个人的指纹图案都是独一无二的，这一事实

makes them particularly strong evidence in criminal cases.

使它们成为刑事案件中特别有力的证据。

However, the system isn't infallible.

但是，该系统并非万无一失。

Prints are often smudged, distorted, or overlapped with other prints,

印刷品经常会被弄脏、 失真或与其他印刷品重叠，

which can make matching more challenging.

这会使匹配变得更具挑战性。

And it’s prone to human error—

而且它很容易出现人为错误—

one 2011 study found that fingerprint experts falsely identified

— 2011 年的一项研究发现， 指纹专家错误地

two different fingerprints as a match 0.1% of the time.

将两种不同的指纹识别 为匹配的比例为 0.1 ％。

While this may seem low, the stakes are high for a wrongly accused defendant.

尽管这可能看起来很低， 但对于被错误指控的被告来说，风险很高。

Further, there’s no universal standard on the number of ridge details

此外，对于专家必须分析 才能匹配的山脊细节数量，

that experts must analyze to make a match.

没有通用的标准。

Many investigators stress that no conviction should be made

许多调查人员强调，不应仅凭

on fingerprint evidence alone.

指纹证据定罪。

For these reasons, forensic experts continue to work to improve

出于这些原因，法医专家继续努力改进

and standardize the fingerprinting process.

和标准化指纹识别过程。

After all, when it comes to investigating crime,

毕竟，在调查犯罪方面，

fingerprints have certainly left their mark.

指纹肯定留下了印记。