In this blog I’ll give you an example of how a major incident can be averted thanks to a criminal who wasn’t exactly the sharpest tool in the shed!

I dealt with a job a few years ago at a very large building, which must have around 4 floors. For professional reasons I won’t name the building, so you’ll have to visualize it yourself.

Entry was gained by forcing open a set of doors around the back, which didn’t put up much of a fight. The offender then went into the bar area, poured accelerant over a sofa and set it alight. The criminal then fled, exiting the building the same way they entered, ironicallythrougha set of fire doors.

There was nothing stopping the offender entering any room in the building, but they didn’t venture anywhere else. Thankfully, the sofa was flame retardant, and the fire had just died out. Had they read the large labels under the cushions a different target may have been selected.

This gave the company a chance to secure their building more suitably, at the loss of a few slightly damaged cushions. I advised the company that people cannot obtain degrees or higher education in criminal activity, and every now and then we’re reminded of this fact.

The snow has cast a wintery blanket on our familiar world, and created an unavoidable path for those choosing to take it. For forensic examiners we usually look out for those ideal surfaces to leave footwear marks on, whether it be a muddy, unlooked after flower patch or a shiny clean window sill. But the snow has given us another route for evidence. Like airports, railways and highways, we need to be well prepared.

Here we have a roof which has been climbed on, and it appears someone has climbed over the railing onto a set of stairs. The footwear marks on the roof are a good indicator showing how many offenders there might be, unless the bad guys have a good leap, or taken up piggy-backing as a hobby!

The marks aren’t always ideal, with parts of the sole missing in this mark. But look at the detail in that top part of the shoe!

Now to add a little snow wax. This hardens the footwear mark before we add the cast, and requires quite a few coats. I’ll spray the mark 5 or 6 times as recommended before adding the cast, and it makes the mark a brown colour.

Now if we wanted to photograph the mark, the camera would be a little happier. Zooming in to get rid of all that white then using a torch or flash will help to show all of that detail a little better, as a bright background would over-expose the image. After waiting around 10 minutes it’s now time to add that plaster cast.

Now if you walked past that in the street you’d probably take a second look. Not the most attractive looking thing! I left the cast for a good hour and a half to dry. Quite a long time, so it’s best to do this first thing.

Time goes by and it’s now time to lift it, and here’s the result.

Bother, that’s not great. I even read through the instructions! Thankfully this was a training exercise I carried out, and not the real thing. And lucky it was, as all mistakes must be learned from. When I next tackle a footwear mark in snow I’ll add more layers of wax before applying the cast, and maybe do a tester mark next to the offender mark to make sure all goes well. I guess this is why some people steer away from the instructions! I’ll go against the recommended 5-6 layers and add around 10, that should do it.

In the real world the footwear mark would be photographed with a macro lens and scale beforehand, so we’ve always got other options. Next time I’m called out and half asleep I should be better prepared to tackle those marks in the snow.

A boxed up footwear cast I took yesterday. Some great zig-zag pattern detail. #footwear #forensics

1/2 - Location of where a tiny blood stain was found on the back of a shirt. Check out the close up… #forensics

2/2 - Close up of a tiny blood stain on a shirt. What a great find. #forensics

Live from the fingerprint table! Red Granular powder used on a plant pot, sadly no suitable ridge detail. #fingerprints #forensics

Blood, as most of you know, is a great source of DNA. Whenever there’s blood at a scene there’s a good chance of catching the offender, or in some cases identifying a victim. Blood has been glamourized by television, and is the centre of shows like Dexter. I’ve seen how characters in these programmes take swabs of blood and parts of it are accurate, but some aren’t. I will go over the process of what I do when I swab blood, and explain my actions.

Here we have a red stain on a window. There’s been vandals in the area and, if this stain is blood, it will tell us whose been hanging around here. Our Detectives can then interview the person and ask for reason’s why their blood was found. I’ll do my photography first - taking long, mid-range and close up shots of the blood.

Then we’ll want to see if it is blood. I’ll start by taking a very small sample of the blood using a piece of filter paper. I’ll fold the paper twice to create a point, and rub it against the edge of the blood stain.

I have two chemicals I use as a presumptive test. On the television you normally see them use just one chemical, and the blood turns a pink colour. For me the test should turn the same pink colour, but only after I add the second chemical. I use Kastle Mayer and Hydrogen Peroxide, which reacts at the presence of hemoglobin. Kastle Mayer is dripped onto the filter paper first, followed by Hydrogen Peroxide. I always remembered which one was first by linking it with a brand of peanuts: K comes before P, Kastle before Peroxide, KP nuts!

This is only a presumptive test and not a definite indicator, so you need to allow for some discretion. I’ll then take a swab of the blood stain using a wet swab. I use a small capsule of sterile water and drip it onto the first ‘wet’ swab. I’ll load up the swab with a decent amount of blood.

I normally take a dry swab too, going over where the blood was to mop up any of the stain left behind. Some SOCO’s choose not to do this and rely on their one wet swab, but it’s just my preference. There’s no right or wrong.

‘Control swabs’ are swabs without any blood/crime-stain on, but are taken so the Scientist knows what background contaminants are on the main swab. For example, you may take a swab of blood from somewhere heavily contaminated with skin cells. I’ll take a background control swab of the area away from the blood stain, so the Scientist can identify what should and shouldn’t be on the main blood swab. It’s a bit like spot the difference - the difference between the background control and the main wet swab should only be the crime stain (in this case blood). This will always be a wet background swab, so there’s a control sample of the water too.

A ‘batch control swab’ is always retained at our main Forensic base. This is a plain, unopened swab from each batch. If a batch of swabs has been contaminated when being manufactured, the batch control swab should be able to tell us.

So if you ever see me swabbing a crime stain and it looks like I’m missing it don’t worry, I’m probably taking a control swab.

The swabs will then get sealed into an evidence bag, ready for me to submit to an Independent Forensic Provider, and hopefully help close the investigation with a positive result.

Doing a training exercise for a new colleague and getting them more familiar with glove marks #forensics

Me ‘suited and booted’. #forensics #soco

Image of #Fingerprints #forensics