Extra Notes Chapter 4 - Extra: Chain of Evidence
In this chapter, Yan Xie finds the slider of a zipper at the crime scene. And because he’s rich, he immediately narrows down the zipper as a Fendi bag, exclusive to the current season, which leads the investigation to Chu Ci. Because this chapter lacks anything noteworthy to comment about, I’ll mainly be discussing the usual mistakes most authors make in a police drama.
Firstly, Yan Xie finding the slider has completely left the chain of custody (CoC) which refers to “the chronological documentation or paper trail that records the sequence of custody, control, transfer, analysis, and disposition of physical or electronic evidence” (Wikipedia). Even if the crime scene was sealed off, the fact is the zipper itself would have been carted as possible evidence on the scene. Here is a weak link in the logic behind the investigation, and it’s not helped by the fact that the zipper wasn’t put in a proper evidence bag - the type made of paper which you inscribe the name, time and type of evidence.
One theme emphasised by Jiang Ting throughout the novel would be ‘every crime leaves a trace; there is no untraceable crime, only an investigator who doesn’t work hard enough’. In forensic science, this is Locard's exchange principle. The principle, expressed by forensic pioneer Dr Edmond Locard, holds that the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence.






