你指的是案情還是愛情

最近 Friends 看一看又跑去看痞子英雄，第九集中藍西英（張鈞甯飾）對跟陳琳（陳意涵飾）關係糾結不清的吳英雄（趙又廷飾）說了幾句意味深重的話：

「你知道刑事鑑識之父曾經說過一句名言，兩個物體接觸之後，一定會產生實質的轉變，從這一個傳遞到另一個，一定有什麼事情被改變了，多了什麼或者是少了什麼，或許答案早就很清楚的擺在你眼前，只是你自己沒有發現，所以才這麼苦惱」

身為宅男的我，遇到這種劇情，自然是要打破砂鍋 google 到底，最初這句話是由一位二十世紀的鑑識科學家 Edmond Locard 所提出的「Every contact leaves a trace」，後來被稱作 Locard's exchange principle（羅卡定理），也可以解釋成 with contact between two items, there will be an exchange。

後來 1953 年 Paul L. Kirk 又做了詳細的解釋：

Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.

所以該說刑事鑑識之父是 Edmond Locard 還是後來提出解釋的 Paul L. Kirk 呢？不過很巧的是，在 2006 年，有一位叫 Colin Evans 的作者出了一本書，書名剛好就是 Father of Forensics，但是不巧的是，裡面寫的卻是另一位著名的當代鑑識科學家 Bernard Spilsbury，但似乎跟這句名言，又扯不上什麼關係。

「你指的是案情…還是愛情」