Cleaning Blood Creates a Clean Spot…Duh!

Bloodstained Sink

Criminalists are sometimes called upon to detect evidence at crime scenes in which the suspect, or suspects, have made efforts to “clean-up” the evidence. Most of the time this involves the cleaning of blood evidence.  Let me start by saying that criminals in these situation don’t usually do a great job. Most of the time they will focus on the blood that they can see. I know that must seem obvious but blood (especially spatter) can find its way into all kinds of places (like the back of a door) that the criminal doesn’t think to check.  Sometimes the color of the surface containing the blood makes it difficult to see (like dark carpeting).

Secondly, criminals typically clean to the point that they no longer see the blood.  The blood may still be detectable using a variety of devices or techniques (no I can’t tell you the best ways to clean up blood).  A lot of the scenes I’ve processed were just cleaned with a water-soaked towel. This just dilutes the blood and spreads it around. Also, the suspect may clean the scene and then forget to clean the clothes they were in while cleaning. There are a lot of variables you could work into a storyline.

Regardless of how it is done there is one constant variable found on scenes that have been cleaned up (assuming you arrive within a reasonably short time after cleaning) and that is a clean spot.  Actually, in some homes a clean spot stands out more than blood spatter. I know that sounds far-fetched but it’s true. It’s the first thing I look for after considering the information I have about the crime (i.e. he was stabbed in the living room). But if there isn’t a clean spot then it’s likely there was no clean-up. Sounds simple right? Not so.

I once was called to a scene of a shooting where the suspect/victim walked into his apartment and cleaned his wound while waiting for the ambulance. All indicators and evidence were that the shooting occurred outside. Police arrived quickly and secured the scene. There was a lot of visible (not cleaned up) blood in the apartment in all the places you would expect given the story. However, the ADA still wanted every single item, even the folded socks in the sock drawer, treated with Luminol. There was no explanation given as to why the suspect would wash his socks in the drawer and leave all the other blood visible, it was just one of those Nike moments…Just Do It. Is this a common thing? I don’t think so but it illustrates that not everyone values the conclusion that if something has been cleaned…it should look “clean”.

So if you’re writing a scene in which CSI’s are processing a scene for latent blood you might want to add some comments about how the area looks differently than the rest of the room, or house, or wherever they are.