Somebody keeps drinking the single source Ethiopian yirgacheffe coffee that I bring to the office for myself.

有人一直在偷喝我帶到辦公室的衣索比亞耶加雪夫咖啡。

I rounded up five suspects from around the office and fingerprinted them. To see if I could find a match from a print, I found on my mug.

我從辦公室周圍找出五名嫌疑人以及他們的指紋，看我是否可以找到和我杯子上發現的指紋吻合的人。

Is fingerprint analysis reliable enough to pin somebody to this unspeakable crime, and more importantly... uhhhh... how do you actually do this?

指紋分析是否足夠可信，足以將犯下這個詭異罪行的人定罪，更重要的是...呃...你要如何分析指紋？

To help me figure out what the hell I'm supposed to do, I brought in an expert.

為了幫助我弄清楚，我到底該做些什麼，我帶來了一位專家。

My name is Peter Valentin.

我的名字是 Peter Valentin。

I'm an expert in crime scene reconstruction and forensic science.

我是犯罪現場重建和法醫學方面的專家。

A fingerprint is probably the most important piece of information when we don't have a known connection between the victim and the offender.

當我們無法找到受害者和加害者之間關聯性的證據時，指紋可能就是最重要的資訊了。

We have to find something that people leave at scenes relatively easy and something that is unique enough that finding it and identifying what it is will lead us back to the person.

我們必須找到人們相對容易遺留在現場以及具有足夠特徵的東西，並藉著它可以找到罪犯。

In order to find a fingerprint, investigators will either use a physical component like a powder–

為了採集指紋，研究人員將使用一些具有物理特性的物質像是粉末 –

So not cocoa powder?

所以不是可可粉？

Cool cool cool cool.

酷喔。

Or a series of chemicals that make a print visible on a surface.

或是足以使指紋顯現的一些化學藥劑。

Our fingerprints have ridges and furrows that align to create unique, recognizable patterns.

我們的指紋有凸紋及凹紋，它們排列在一起構成了可識別的圖案。

There is a what's called a loop right here, you have ridges that are coming into the pattern and then coming back out.

這裡有一個所謂的箕形紋，凸紋繞了一圈然後又回來了。

Here's another loop right here.

這是另一個箕形紋。

There's arches, and there's whorls and those those three categories alone comprise at least 95 percent of the fingerprints that are in the database.

這是一個弧形紋這是斗形紋，資料庫中至少 95％ 的指紋是由這三種類別構成的。

Everyone's fingerprints have unique features that differentiate them from everyone else's.

每個人的指紋都有獨一無二的特徵，足以與其他人區別。

For instance, this ridge splits into two here and this ridge has a break in it.

比如這個凸紋在這裡分叉，這個凸紋在這裡有一個缺口。

These patterns remain the same throughout a person's lifetime, which makes them a powerful identification tool.

這些指紋圖案一生都不會改變，這使得它們可以成為強而有力的識別工具。

My fingerprint is pretty easy to spot.

我的指紋很容易識別。

The pattern looks like a 1998 Chrysler Sebring.

圖案看起來像 1998 年份的克萊斯勒．賽百靈汽車。

Investigators rely on the characteristics of a print to find a match using a method called ACE-V.

鑑識人員依據指紋的特徵，使用一種叫做 ACE-V (Analysis, Comparison, Evaluation, Verification) 的方法來找出另一個相符的指紋。

First, they analyze the print and the surface it's on to see if it's viable for examination.

首先，他們分析指紋和其所在物體的表面，看它是否適合做採樣檢查。

This one's great.

這個很好。

This one, not so much.

這個就不太行。

Then, they take the suitable print and compare it against known fingerprints looking for points of similarities and differences.

然後，他們將指紋印出來與已知指紋進行比對尋找相似點和不同點 。

For example both these patterns are whorls and bifurcate right here.

例如，這兩種圖案都是斗形紋和這裡有分叉。

Investigators look at these traits and try to gauge if there's enough points of comparison to declare it a match.

鑑識人員會查看這些特徵，並試著判斷這些特徵是否足以來斷言兩個指紋是相符的。

Finally, a qualified peer reviews their conclusion to verify the match.

最後，由一個有資格的同事來審核他們的結論，以確認相符。

After using high tech software to analyze the prints from my mug – I'm kidding this is just some stock footage I downloaded.

藉由高科技軟體來分析我杯子上的指紋——我是開玩笑的這只是我下載的一些鏡頭。

I think I finally found a match.

我想我終於找到相符的指紋了。

But, ok, even when it's done by professionals... how reliable is fingerprint analysis?

但是，好吧，即使是由專業人士完成的...指紋分析到底有多可靠？

It's a useful tool that obviously has value, but I think it's problematic to overstate its value, especially in a criminal justice context.

它是一個既有用又具價值的工具，但我認為它的價值被誇大了，尤其是在刑事司法的層面上。

One accuracy study found that examiners made false positive identifications in 0.1% of cases.

一項準確性研究發現，指紋分析員在其審查鑑定為真的案子裡有 0.1％ 判讀錯誤。

Which means identifying a print as a match when it's not.

這意味著被識別為符合的指紋，實際上是不符合的。

That doesn't sound too bad... unless you happen to be one of those false positives.

這聽起來好像還沒那麼糟......除非你碰巧是那些被判讀錯誤的當事人之一。

Brandon Mayfield, a lawyer from Oregon, was one of those unlucky few.

來自俄勒岡州的律師 Brandon Mayfield 就是其中一個倒楣鬼。

He was falsely accused of the 2004 Madrid train bombing because the FBI made a false positive match with a partial print found at the scene.

他因 2004 年馬德里火車爆炸案而被誣告，因為聯邦調查局在現場發現的不完整的指紋，被鑑定為與他的指紋相符。

Mayfield seemed like a good suspect to investigators because he had recently converted to Islam and was the lawyer for a man who attempted to join the Taliban,

Mayfield 似乎是一個值得被好好調查的嫌疑犯，因為他最近改信了伊斯蘭教，並且是一名試圖加入塔利班恐怖組織者所雇用的律師，

which in the wake of 9/11 were all red flags for the FBI.

在 911 事件之後他們都是聯邦調查局鎖定的危險人物。

There was a bias that existed because once they tentatively identified the unknown fingerprint belonging to this individual,

這裡存在著一種偏見，因為一旦他們暫時將未知的指紋識別為屬於這個人，

who he was and what his background was made the identification seem stronger than it actually was.

一旦知道他是誰，他的背景是什麼，就會造成鑑定的結果被強化而超過了其原有的證據力。

He didn't have a valid passport.

他未持有有效的護照。

So it's a little implausible on the face of it that he was handling a bag of detonators in Spain.

所以從表面來看，他正在西班牙處理一包炸彈引爆器，這有點令人難以置信。

Fingerprinting was so powerful that it just sort of it trumped everything else.

指紋識別的證據力是如此強有力，以至於它凌駕了一切。

Mayfield was even given his own analyst to examined the prints, and even they agreed that it was a match.

Mayfield 甚至被允許由他自己雇用的分析師來檢視那些指紋，結果連他們也認為指紋是相符的。

That's an interesting thing about bias because, you know, everybody's assumption is that the experts are biased toward the side that they're working for.

關於偏見，這是一個有趣的事情，因為，你知道，每個人的假設都是專家偏向朝他們正在努力的目標進行。

Here was a guy who was working for Mayfield and yet he corroborated the evidence against him which turned out to be incorrect.

這是一個為 Mayfield 工作的人，而他證實了那些對 Mayfield 不利的證據結果是錯的。

The FBI released a 330-page report about where their analysts went wrong, and it's pretty much a case study in a lot of the potential downfalls of fingerprinting.

聯邦調查局發布了一份長達 330 頁的報告，指出他們的分析師出錯的地方，而在眾多潛在的指紋識別失敗的例子中，這似乎值得作為一個研究案例。

They cited things such as ignoring differences between the prints, lack of independent verification, the pressure of working on a high profile terrorism investigation,

他們引用了諸如忽視指紋之間的差異、缺乏獨立驗證機制、高度恐怖主義調查工作的壓力，

and letting bias about the suspect affect their analysis.

以及對嫌疑人的偏見影響了他們的分析。

Their report summed it up by saying, "in any human endeavor, there is a potential for error."

他們的報告總結說：「不管人類如何努力，都有可能出現錯誤。」

You know, I would suggest learning from history and realizing that none of these things are going to be error free.

你知道，我會建議從歷史中學習，並意識到任何這些事情都不可能百分之百正確。

So there's going to be mistakes and errors and screw ups.

因此，免不了會出錯並搞砸。

But also evidence is inherently probabilistic.

但證據在本質上而言也是概率性的。

So even though it's not a perfect tool, until a more reliable technology emerges, law enforcement will continue to utilize fingerprint analysis.

因此，儘管它不是一個完美的工具，但在更可靠的技術出現之前執法部門將繼續使用指紋分析。

And I won't ever be fully certain of who stole my coffee.

我永遠無法百分之百確定誰偷喝了我的咖啡。

Until I catch him on this new surveillance camera that I installed.

直到我可以用這台新安裝的監視器抓到他為止。