英语听力文摘480 如何破无头绪凶杀案？

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辩论术/ 法医学

A murder has been committed. The scene of the crime is a secluded area. There were no witnesses, and the body is considerably decayed.

As the chief investigator, you have a suspect who was in town a week ago. But to convict him, you'll need to know the date and time that the victim was murdered. How can you tell? And besides, what’s that annoying buzzing in your ear? Wait, don’t swat that fly! He’s your star witness. In fact, that little fly just told you the date of the crime!

Flies don’t carry pocket calendars, and they can’t testify before a jury. How can a crime-scene insect help a police investigation? By doing what it naturally does–eating and laying eggs.

When someone dies outdoors, the first investigators on the scene are usually bright greenbottle blowflies. Attracted by the smell of decaying flesh, these usually arrive within ten minutes of the death. While this smell might make us retch, for the blowfly it’s as savory as grandma’s apple pie. The blowfly’s scientific name is “Sarcophagi,” which means “corpse eater.”

While they eat, the blowflies lay eggs in the softer parts of the body, and these hatch into maggots twenty-four hours later. These maggots attract other insects, like the predatory rove beetle(隐翅虫), who feast on them. And so on. Wave after wave of hungry insects arrive, marking time as accurately as a clock.

Meanwhile, the blowflies follow their natural life cycle. Maggots become pupae, the pupae become adults. By surveying the insects in and around a corpse, forensic scientists can help a police investigator determine how long ago a victim was murdered.

有一场凶手案。凶案现场是一个隐蔽的地方，没有目击证人，尸体也严重腐烂了。

身为首席侦查员，你在一周前就在镇子里有一个怀疑对象。但是要证明其有罪，你需要知道受害人被害的日期和时间。你要怎么说呢?除此之外，你耳朵里那些恼人的嘈杂声又是什么呢?等等，不要拍打这只“苍蝇”，它就是你的重要目击证人。事实上，这只小苍蝇就告知了你犯罪日期。

苍蝇并没有在兜里自带日历，它们也不能在陪审团面前作证。那一只在犯罪现场的虫子是怎样帮助警察调查的呢?通过它们正常的方式—— 食用(尸体)并产卵。

当一个人死于户外时，到现场的第一批侦查员通常都是亮亮的绿头苍蝇。他们被正在腐烂的肉味所吸引，通常在死亡后十分钟内就到来了。这些(腐肉)气味或许会令我们作呕，但对于绿头苍蝇来说他们就像是外婆做的苹果派一样可口。绿头苍蝇的学名是“Sarcophagi(中文意思为“石棺”)”，意思是“尸体食用者”。

这些苍蝇一边嗜(尸体)，一边在尸体较软的地方产卵，然后这些卵又会在24小时后会孵化称蛆。蛆又会引来其它的昆虫，比如说以蛆为食的肉食型隐翅虫等。饥饿的昆虫们一波接一波的到来，时间精准的跟时钟一样。

与此同时，绿头苍蝇们继续这它们的正常生命循环。蛆变成蛹，蛹再长大。通过调查尸体周围的昆虫，法医可以帮助警方调查人员确定受害者遇害的时间。