英国新闻听力 刑警或可通过香水追凶（在线收听）

Should detectives be sniffing out criminals literally? Could their noses be as useful as their eyes in the hunt for clues?

We are looking to determine the potential of perfume to act as a form of trace evidence. But in order to do so, we need to understand how perfume transfer from one piece of fabric to another. Only when we have an understanding of that, we can assign evidential value to that trace evidence.

And what is trace evidence?

So trace evidence is anything that is found at the crime scene in very small amount. It can be anything from dust, to pollen to gunshot residue.

So these are traditionally physical things but you are looking at a scent.

Yes. Yes. We are looking at scent. For example, there’s a lot of studies done on the scent of explosives, of drugs, for example marijuana or cocaine.

Well, you are specifically looking at perfume?

Yes, perfumes are widely used. They are used on a regular basis by both men and women.

We have the analytical technique. And it’s a very accurate and reliable technique. So putting these together, we can obtain a lot of information.

And what types of crimes are we talking about here?

It would have to involve contact.

Human to human?

Yes, it’ll be physical contact that will involve some transfer of fragrance from one piece of fabric to another or to this kin.

So it will be something like sexual assault or for example a pub fight, anything that involves contact.

And what does your research suggest, I mean how accurate can detectives be in tracking down someone from their perfume?

There are many variables that affect the transfer of the perfume, but also the persistence.

I was looking at for how long a perfume stays on a fabric before transferring. So if the offender had perfume on his fabric that was one day old or seven days old, how that influences the transfer onto a secondary piece of fabric.

So how many days potentially would police forces have for this evidence to be credible?

We saw that after seven days, we found 6 perfume components out of the 44 originally identified in a male perfume.

But to be clear, this is not like DNA evidence.

Yes, I think there is a very clear difference between DNA and all other forms of trace evidence and that would include perfume evidence.

And this will just be one bit of evidence. You suspect that this wouldn’t be, you know, the piece of evidence that could be used in court and specifically identify a killer.

刑警真的应该通过嗅觉找出犯罪分子吗？在搜寻线索方面，他们的鼻子可以和眼睛一样灵敏吗？

我们想确定香水是否能作为一种痕迹证据，为此，需要了解香味从一块布料转移到另一块布料的过程。只有掌握了这一点，才能给这个痕迹证据添加证据价值。

什么是痕迹证据呢？

痕迹证据是在犯罪现场发现的非常少量的东西，从灰尘到花粉再到涉射击残留物都有可能成为痕迹证据。

所以传统上这些都是实物，但你们研究的是气味。

对，对，我们研究的是气味。比方说，关于爆炸物以及大麻和可卡因等毒品的气味有很多研究。

而且你们具体研究的是香水？

没错，香水的使用非常普遍。男性和女性都会经常使用香水。

我们拥有特定的分析技术，非常准确可靠。把分析结果汇总起来就能获得很多信息。

那我们在这里讨论的具体是哪些犯罪类型？

涉及接触的犯罪类型。

人身接触？

是的，身体接触，因为其中涉及香气从一块布料转移到另一块布料或同类物质的过程。

所以一般是性侵案或者比方说酒吧斗殴等涉及身体接触的案件。

那你们有什么研究成果，换句话说，刑警通过香水追捕嫌犯的准确度可以达到多高？

影响香水的转移及其持久性的变量有很多，我一直在关注香水在布料上停留多长时间才会转移，如果犯罪分子衣服上的香水是昨天或者一周前喷的，会对香味的转移有什么影响。

那将来警方大概需要几天才能确认这个证据呢？

我们发现，7天后可以在男士香水原有的44种成分中找到6种。

明确一下，这种证据不同于DNA证据对吧？

对，我认为DNA和其他所有形式的痕迹证据都大有不同，其中就包括香水证据。

而且这只会成为证据中的一种，你认为它不会成为可以在法庭上使用的或专门用于认定凶手的证据？