Innocuous Evidence: The CSI Curse

Are the Missing Knives Relevant?

Crime scenes can occur just about anywhere but most often they happen in places with a lot of human activity not related to the crime. Take your average residence or even a convenience store. Stuff is happening there all day every day right? All of those activities leave behind “evidence” just as criminal activity does. The only difference is that CSIs don’t generally care if so-and-so threw a candy wrapper on the floor, brewed a pot of coffee, or left their newspaper spread out all over the table because none of these activities are a crime.

I often tell young criminalists that CSIs are not “garbage collectors”. Simply put, we can’t collect everything from a crime scene. You have to use your training and experience as a filter to take items which actually support or refute the legal elements of the crime. Aside from the physical requirements needed to house all these items you also have to make sense of them. This is where theory collides with reality and hinges upon the fact that as criminalists we can not know the complete history of any location (all activities that occurred there). Exhibit A: innocuous evidence.

Innocuous evidence are items that have significance to an individual but do not possess any quality making them suspicious to the average detective. It might be an item of jewelry left on the night stand, a coffee mug on the kitchen counter, or a baseball cap on a chair. CSIs easily recognize the significance of things like fired cartridge cases, bloodstains, or drugs. These items are commonly encountered and generally yield probative information about a crime. They are what I call Tier1 artifacts.

Are Any of These Items Significant to the Crime?

But as I noted above, crimes often occur in centers of non-criminal human activity so deciding what items (or conditions) relate to the crime and what items (or conditions) are simply the result of human occupation can be tricky. There is a great scene in the movie Seven with Brad Pitt that illustrates this point. In the movie, the widow of a recent homicide victim is asked to look at photographs of the crime scene to see if anything looks out-of-place. After studying the photos she notices that an abstract photo on the office wall is hung upside down. You’d never notice that unless you were intimately familiar with the canvass and its normal orientation.

This is great news for authors because it provides a lot of opportunities to inject significant items or conditions that may go unnoticed at first but then serve to blow the case wide open later on in the story.  Select something that blends into the crime scene environment and wouldn’t seem suspicious to the detective or CSI. It might be something in the victim’s purse or vehicle that is tangential to the crime scene. It could be a receipt to a place the victim would never go for some reason but the average person would. Only someone who really knew the victim would recognize that. Following up on the lead maybe your character gets a copy of the surveillance tape showing the victim and the suspect.  However you use it, innocuous items are common place at crime scenes. 99% of the time they aren’t related to the crime but once in a while they may break a case wide open.