Under Arrest - L is for Luminol

Image by Clker-Free-Vector-Images from Pixabay 

Welcome back to A-Z - today's letter L is all about Luminol. 

I was talking about different types of evidence, and blood is an important one as it can help determine what happened, plus it contains DNA that may be used to match to an existing profile in the database or at least to create a snapshot composite sketch like they did for April Tinsley's killer.

According to crime shows many criminals try to clean up the bloody mess that their actions literally created. Unfortunately the strong smell of bleach makes cops suspicious as soon as they approach the crime scene. 

Also, even if the killers did a great job applying white vinegar to neutralize the smell, traces of (even old) blood can still be detected by using Luminol, a chemical that reacts with the iron in hemoglobin. 

Officers like to say "the crime scene lit like a Christmas tree".

Photo Source
When Luminol is sprayed evenly across an area, trace amounts of an activating oxidant make the Luminol emit a blue glow that can be seen in a darkened room. The glow only lasts about 30 seconds, but investigators can document the effect with a long-exposure photograph

What happens next? 

Pattern analysis looks at the physical characteristics of the stain patterns including size, shape, distribution, overall appearance, location and surface texture where the stains are found. 

Reconstruction uses the analysis data to put explanations to the stain patterns: What type of crime has occurred? Where is the person bleeding from? Did the stain patterns come from the victim or someone else? Are there other scene factors (e.g. emergency medical intervention, first responder activities) that affected the stain patterns?

To help reconstruct events that caused bloodshed, analysts use the direction and angle of the spatter to establish the areas of convergence (the starting point of the bloodshed) and origin (the estimation of where the victim and suspect were in relation to each other when bloodshed occurred).

The analyst may presume the victim was either lying or sitting on the floor. If it is five feet above the convergence, the victim may have been standing. This analysis can be done using strings and a protractor, mathematical calculations or computer models.

I find this highly interesting. 

There was Richard Chase, an infamous serial killer from the 70s, known as the vampire of Sacramento for obvious reasons. He didn't think Bloody Mary was an appropriate drink, he went straight for the real blood. Read up about him at your own risk, be warned though, it is very, very graphic. 

He ended up getting caught and given the death penalty. However, he beat the system to the punch by overdosing in his cell, sparing the tax payers lots of money that would have gone into appeals, hearings and incarceration in solitary confinement.

Having an identical twin could have helped him to walk free back then. These days even though in general identical twins have the same DNA, a special epigenetics profile may get you busted. Also their fingerprints, while similar, may still be distinct enough to charge the guilty twin.

Whoa, I say you have just deserved yourself a drink -anything but a Bloody Mary, though! Let me know your favorite happy hour beverage and please come back tomorrow for the letter M - no blood, I promise!

Image by Gerd Altmann from Pixabay


  1. Richard Case sounds like a Hollywood movie, surprised i haven't heard of him or one about him. Say are you going to talk about people who use sleepwalking as a defense for murder? that'd be a fascinating one for "S".

    Cheers, Joy at The Joyous Living

  2. Very interesting. We've been watching a lot of the Law and Order SVU's and I know I've heard that "lit up like a Christmas tree" at least once!

    Janet’s Smiles

  3. I am sure every man and his dog have heard of luminol

  4. Interesting theme - I love crime scene investigating shows. And congrats on making it to L! Visiting from the A to Z. www.shirleyjdietz.com/04/12/2019/layer-cake-geology/

  5. Having an identical twin isn't enough doubt any longer? That's good to know.


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