Before I begin you need to know about Edmund Locard, a pioneering forensic Scientist who in 1934 formed the theory known as Locard’s Exchange Principle – “Every contact leaves a trace”
This is the basis of all forensic examination of crime scenes.
1. Police Cordon – Cordons are put in place to ensure that vital evidence isn’t lost by allowing everyone in to trample their way through the scene. A log is kept detailing everyone who enters, why they are there and the date and times they arrive and leave.
2. CSI – Crime Scene Investigators attend crime scenes to examine them for evidence to help prove or disprove someone’s involvement in the incident.
3. Witnesses – Police will ask as many people as possible for their version of events to help get a full picture of what happened.
4. Victims – A lot can be determined from a victim of crime. From their statements detailing their account of what took place and from evidence left on themselves or their clothing.
5. Police officers – often present at crime scenes to take statements, to log exhibits, to man the cordon to record anyone entering and to prevent entry from others.
6. Photographers – Attend to film and photograph serious crime scenes. Photographs capture exactly what is present and can serve as a visual representation to show to others who were unable to see the scene in person.
7. Suspects – Sometimes suspects are found at crime scenes. It could be that they have reported the crime themselves and are pretending to be a victim might or that they are still on scene when police arrive. Like victims, suspects will give us their version of what has happened and may carry a whole host of evidence on their person.
Not every suspect is guilty of the crime they are thought to be linked to so it is vital to get as much information from them as it might rule them out of the investigation or put them firmly in the middle of it.
8. CSI tape – this is to mark the cordon and has a knack of bringing everyone in the vicinity to the area as if it were a magnet.
9. Fingerprints – my favourite! I could go on about these for hours but suffice it to say that they remain the only positive means of identification. Yes, DNA is fabulous, but identical twins will have identical DNA whereas no 2 people, even identical twins, will have the same fingerprints.
10. Shoemarks – Until we can fly, we will always leave shoe marks wherever we tread. There are many ways of recovering shoe marks depending upon the surface they are on.
11. Hairs – We regularly inadvertently leave our hair behind throughout the day without event noticing. It contains DNA which can identify who it has come from.
12. Fibres – much like hair, our clothes will shed fibres and as they encounter other materials. Fibres will be transferred from one to another (remember what Locard said?) We recover fibres by plucking, taping, brushing, sweeping and forensic scientist inspect them microscopically to look for matches.
13. Indented writing – this is cool. Remember as a kid you’d crayon over a page in a notepad to see what had been written on the previous page? A more sophisticated method is used to achieve the same result without damaging the exhibit.
14. Blood – Blood at a scene can identify both victims and culprits through DNA and can determine what took place by the blood spatter patterns left behind.
15. Semen – Often found on clothing (victim and suspect), skin, furniture, bedding, condoms etc. Contains DNA so can determine who it has come from.
16. Weapons – when we think of weapons we often go straight to guns and knives, or of course the obligatory candlestick in the library. Some weapons are taken intentionally to a scene and some are items picked up and used spontaneously. Whatever has been used in a physical attack needs to be found and isn’t always at the crime scene itself. Officers spread the search far and wide to locate weapons if necessary.
17. Bodies – sadly, some crimes leave individuals dead and the body itself becomes a scene. A post-mortem examination of the corpse will help to determine what happened to the person.
18. Footprints – like fingerprints, the ridge detail on our feet and toes is unique and can help us to identify individuals. Any footprints found at a crime scene will be recovered but can only be compared against suspects whose footprints are taken in relation to the offence in question. This is because unlike fingerprints, there isn’t a national database of footprints!
19. Text messages – It’s amazing how much our phone records can tell us. Times of messages and calls as well as content of text messages can be of enormous evidential value. You might think that you’ve deleted something, but there will always be a record of it and high-tech crime units have the power to recover data in minutes.
20. Drugs – It’s not all like Breaking Bad, but set ups are often similar and run from normal looking residential homes. I have been to countless “cannabis factories” set up in lofts, and once attended a 3 bedroomed house where every room was kitted out with equipment to maintain the perfect conditions for the plants to grow.
21. Broken glass – When glass is broken tiny shards of it will fly out and land on surfaces nearby. Some will be so tiny you they won’t be seen by the naked eye. It is the job of scene examiners to take samples of broken glass from scenes to enable scientists to microscopically compare the glass with any fragments found on suspects clothing, shoes, hair etc. Suspects brought into custody will have their outer clothing taken and hair combed over paper to catch any fragments that are in it. Did you know that we can also determine from which side a piece of glass has been broken by looking at the shape of the stress marks left by the break.
22. Paint – Evidence of paint transfer is excellent when investigating crimes and the transfer can occur in many ways when a crime is committed. For example, when a vehicle hits a person, paint can be transferred from the vehicle to the victim’s clothing. When force is used to gain access to a building, cross transfer of paint can occur. A painted tool may leave paint flakes or smears on a window frame. Similarly, paint from the window frame may transfer on to the tool.
23. Toolmarks – if a tool is used to force something open there will be evidence of the tool used on the surface of the item. Scene examiners take a cast of the impression and scientists can determine the tip width and depth etc and if a suspect tool is found, they may be able to make a positive identification comparing striation marks on the cast against the tool itself.
24. Powder – I’m not talking about more drugs here, but the powder we take into a crime scene. My go to powder for searching for fingermarks was always aluminium powder but there is an array of different powders and colours available and each is chosen according to the surface being examined.
25. Photographs – Essential to recall the scene exactly as it was when it was first found and to record accurately where items are recovered from.
26. Phone records – Who calls have been made to, times and locations of calls etc are all valuable during certain investigations
27. Computer records – Everything that is done on a computer can be traced. Even when it has been deleted. Home computers, games consols and phones are regularly taken away for forensic analysis.
28. Chemicals – Chemicals are used to look for fingermarks that cannot be developed by powder. If these items are portable, they are taken away to be chemically treated in the lab, often they are immovable, so the chemicals need to be taken to and used at the scene.
29. Vehicles – There so much that can be determined from the examination of a vehicle. Dents, scratches, broken lights, tyre tread etc. There is a wealth of information that can be gleaned from linking damage to vehicles to incidents.
30. Lip and ear prints – These are sometimes found on the outside of a window where someone has been looking through to see what’s inside and listening to see if anyone is around. We can take DNA from these prints and get an indication of the height of the person who left them.
31. DNA – Deoxyribonucleic acid is found in every cell (apart from red blood cells) and carries the genetic code for each individual. Only IDENTICAL siblings will carry the same DNA.
32. Clothing – clothing is useful for identifying parties involved in crime from descriptions of what they were wearing as well as evidence found on the clothing itself and from any fibres etc transferred from the clothing to the scene.
33. Exhibit bags- As evidence is recovered it is fully documented and placed into an exhibit bag and sealed. Each bag has a unique serial number on it which is also documented.
34. Arson – fire debris is often thrown outside a building by members of the fire service as they work to extinguish the fire. Scene examiners often work with the fire service to establish how the fire started which often necessitates reconstructing the layout of the rooms prior to the fire by repositioning the items found outside.
35. Gunshot residue – When a firearm is discharged gunshot residue is deposited on the hands and clothes of the person firing it and can travel up to 5 feet from where the gun was fired.
36. Injuries – Cuts and bruising etc on those involved in incidents are recorded and photographed as a lasting record of any injuries sustained.
37. Poo – I’ve lost count of the times I attended a burglary where the homeowner would excitedly be waiting to show me a pile of to examine. What can I say… people get nervous when they’re up to no good!
This list is far from finished as the list is endless and I may have missed off some that to you are obvious and you can’t imagine why I’ve not mentioned them. I’d love to hear what you think I should have included and didn’t.
By Diane Ivory-