Re: CSI demystified! - CSI

>What is the percentage of cases solved using forensic techniques?

A: I don't have a number, but usually forensics is an *adjunct* to plain old
detective work. For example, in my case, I don't go out and bust drug
dealers; all I do is analyze their wares. If the case goes to court, all of
the observations and actions by the patrol officers and the narcotics
detectives (what they did and why they did it) has to be related to the
jury, and comes under scrutiny by the defense lawyers. There has to be
"probable cause" for the arrest. Custody of the evidence has to be controlled
and documented, to insure that it wasn't contaminated or tampered with prior
to its arrival in the lab. My analysis of the evidence is just the end of the
whole process -
and if the analysis shows that there were no drugs present after all (the guy
was selling sugar instead of meth, maybe), then the whole case collapses and
the charges are dismissed. If drugs were actually present, the defendant may
decide to plead guilty and not go to trial. Even if there is a trial, if the
defense counsel is able to show there was a break in the chain of custody of
the evidence (such that the evidence I analyzed might *possibly* not be the
same evidence that was seized from the defendant at his arrest) or that there
was not legal probable cause to justify the arrest, then the case ends. If
all the other requirements are met, then the prosecutor
still has to show that I'm qualified as a drug analysis expert (this is done
based on my educational background and experience) before I can testify about
how I analyzed the evidence and what the results of my analyses were. My
analysis is like the final piece in the puzzle. In cases of rape or murder,
forensic analysis can become the linchpin to the entire case. There have been
a few cases where a person was convicted based on old (pre-DNA) serological
techniques, and
subsequent re-analysis using modern DNA techniques actually *exonerates* the
person. There are also some cases that have been solved via CODIS (Combined
DNA Indexing System - a national DNA database) matches, where traditional
investigative/detective techniques have run into a dead end. Usually though,
forensics provides the "nail in the coffin" that provides the conclusions
formed during the preceding detective work with some scientific certainty.

大約有百分之幾的案件是靠鑑識科技來破案的？

我沒有一個確切的數字，不過鑑識通常是警探工作的附屬品。就我的例子來說，
我並不到外面去抓毒梟，我只分析他們的器械。上了法庭之後，巡警以及緝
毒組探員所做的觀察還有行動〈做了什麼/為什麼這麼做〉都必須呈交給陪審團。
而這些觀察和行動都會被辯方律師一絲不苟的徹底檢查。逮捕必須是有正當理由
的，證物的監護權有受到管制且記錄，以保證在到達實驗室之前沒有被污染或是
動過手腳。我的分析只是整個執法過程的最後一個步驟，如果分析結果顯示證物
裡其實並沒有毒品，〈也許被告賣的是糖而不是脫氧麻黃鹼〉整個案子就終結了
，而檢方也必須放棄告訴。
如果我們證實毒品的存在，被告可以選擇認罪，這時就不需審判。而如果在審判
的過程中，辯方律師可以證明處理證物的過程有瑕疵〈譬如說我分析的證物有可
能並不是在被告被逮捕時所扣留的那份〉，或是警方沒有正當理由去逮捕被告，
這個案子也會被終結。
就算以上的條件都被達到了，在檢方證明我是個有分析資格的毒品分析專家之前
〈這是建築在我的教育背景還有分析經驗上〉，我都不能我為分析的證物還有得到
的結果作證。我的分析就像是拼圖的最後一塊一樣。
在強暴或是謀殺一類的案件中，鑑識工作可能扮演決定性的關鍵。曾經有案件是
靠血清學〈沒有DNA前所用的技巧〉來判定被告有罪，但在重新使用現代DNA分析
後而還給被告清白的。
還有一些本來當地警方使用傳統技巧，卻追進死胡同的案子，是靠著CODIS
〈全國DNA資料庫〉來破案的。
通常鑑識科學可以提供檢調工作一定程度上的科學保證，是拍板定案的闔棺釘。


>Do all cases require CSIs?

A: No, definitely not. Nowadays most drug cases as well as sexual assault
cases will make use of forensic analysis. Murder cases can often make use of
forensics, for trace analysis and/or firearms analysis, and possibly for DNA
analysis. Driving while intoxicated cases depend on analysis for alcohol or
drugs. Burglary cases *may* use forensics (for example to match the tools
used to break in, with the marks they left behind at the crime scene, or DNA
traces). But many other cases, such as domestic violence, simple assault,
fraud, robbery, speeding tickets, streaking (just kidding - are you still
paying attention?) - don't usually involve CSI types.

所有的案件都需要CSI嗎？

不，絕對不是這樣。現今大部分毒品以及性侵害案件都會用到鑑識分析。謀殺案
通常也會使用鑑識科學來做微量證物/槍械，又或者是DNA分析。酒後/吸毒後駕車
也需要酒精/毒品濃度分析。
搶劫案件可能會用到鑑識工作〈如用工具留下來的痕跡來證明使用的工具，又或者
是DNA證據〉。但在大部分的情況下，如家庭暴力、一般侵犯罪、詐欺、搶劫、超速
、露鳥〈開玩笑的，你還在聽嗎？〉，通常是不用CSI出動的。

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