BTEC Level 3 UNIT 32 Forensic evidence collection and analysis

1. BTEC Level 3 UNIT 32 Forensic evidence collection and analysis

2. Lesson Objective • To be able to gather forensic evidence from a simulated crime scene using appropriate methods. • This will include: • Health and safety • Evidence collection • Preservation of scene and sampling • Analysis and evaluation

3. What is forensic science? • the application of a science to answer questions of interest to a crime. • comes from the Latin forensis, meaning "of or before the forum." • In Roman times, a criminal charge would be presented before the public in the forum. Both the person accused and the accuser would give speeches. The individual with the best argument would determine the outcome of the case.

4. Edmond Locard(1877 – 1966) • aka “The French Sherlock Holmes” • formulated the basic principles of forensic science • “Every contact leaves a trace” • Started the first police laboratory in Lyon in 1910

5. Scene of Crime Officer • S.O.C.O. • an officer who gathers forensic evidence at the scene of a crime. • usually civilians, not police officers, but are employed by the police force. • Evidence collected is passed to detectives and to forensic laboratories. • The SOCOs do not investigate crimes or analyse evidence themselves.

6. Health and Safety • Many jobs require you to wear personal protective equipment (PPE). • Activity 32.1A – find a picture of a SOCO and label all the PPE they are wearing, explaining the reason for using it.

7. 32.1B Risk assessment • What hazards might be present here? • What could you do ensure risk is minimised?

8. Contamination The unwanted transfer of material which must be avoid at a crime scene Individuals can contaminate the scene or evidence at any time by: • Leaving fingerprints / hairs / fibres / DNA • Not sealing the evidence properly • Putting more than one piece of evidence in a bag at once • Using old equipment Contaminated evidence can not be used in a court of law and may result in criminals being set free.

9. HSE LeafletActivity 32.1C • You need to make a Health and Safety leaflet for a new SOCO to make them aware of potential risks • You may want to include SOCO PPE and elements of your risk assessment. • Using the website www.hse.gov.uk, you need to find 3 piece of legislation to include in your leaflet.

10. Processing a Crime Scene Correct processing of a crime scene is essential to gather as much information as possible and prevent contamination. STEP 1 INTERVIEW - The SOCO arrives on the scene and makes sure it is secure. An initial walk-through is conducted to get a feel for the crime scene. The first officer at the scene and/or the victim is interviewed to ascertain the "theory" of the case; what allegedly happened, what crime took place, how was the crime committed etc. This information may not be 100% factual but it will give the SOCO a place to start from. The SOCO also needs to find out if anything has been moved. Potential evidence is noted but at this point, nothing is touched.

11. Processing a Crime Scene STEP 2 DOCUMENTATION – Is the "theory" of the case supported by what the SOCO observes? Examine the scene to identify evidence, point of entry and exit, the general layout, etc. The SOCO thoroughly documents the scene as well as any potential evidence by taking photographs and drawing sketches during a second walk-through. Sometimes, a video walk-through may be conducted. Again, nothing is touched.

12. Processing a Crime Scene STEP 3 PROCESSING - Now it's time to touch stuff -- very, very carefully. The SOCO systematically collects all potential evidence, tagging it, logging it and packaging it so it remains intact for further analysis by a crime laboratory. The lab processes all of the evidence collected at the crime scene. When the lab results are in, they go to the lead detective on the case.

13. Search Patterns There are several search patterns available for a SOCO to choose from to assure complete coverage and the most efficient use of resources.

14. Search Patterns 1) Inner Spiral The SOCO starts at the perimeter of the scene and works toward the centre. 2) Outer Spiral The SOCO starts at the centre of scene (or at the body) and works outward. Spiral patterns are good if there is only one SOCO at the scene.

15. Search Patterns 3) Parallel The SOCO team form a line and walk in a straight line, at the same speed, from one end of crime scene to the other. 4) Grid Two parallel searches, offset by 90 degrees, performed one after the other.

16. Search Patterns 5) Zone The lead SOCO divides the crime scene into sectors, and each team member takes one sector. Team members may then switch sectors and search again to ensure complete coverage.

17. Activity 32.1D Search Patterns • You need to investigate the following search patterns: • Quadrant search (Zone) • Link Method • Strip or line search (Parallel) • Grid • Spiral Search (inner and outer) • Wheel or ray method • You will need to include a diagram of the SOCOs pathway through the crime scene. • Also include any advantages and disadvantages of the search patterns. • In your opinion, which would be the most ideal search pattern?

18. What kind of evidence might a SOCO be searching for? • Trace evidence (gunshot residue, paint residue, broken glass, unknown chemicals, drugs) • Impressions (fingerprints, footprints, tool marks) • Body fluids (blood, semen, saliva, vomit) • Hair and fibres • Weapons and firearms evidence (knives, guns, bullet holes, cartridge casings) • Documents (diaries, suicide note, phone books; also includes electronic documents like answering machines, text messages)

19. Lesson Objectives • All will be able to: • identify shoe manufacturers’ tread patterns and wear patterns. • Most will be able to: • describe the stages of footwear analysis. • Some will be able to: • explain the theory of footwear analysis to a jury.

20. Footprints Footprints give information about: • The number of criminals • Points of entry and exit • Position of the suspects • Direction of movement through the crime scene. • Time period (eg short-lived impressions in frost, snow and dew) • Sequence and manner (walking, running, limping, staggering). • The type, size and areas of wear on the shoes.

21. Footprints • Manufacturer, model and size: - general outsole patterns, shapes, features and markings can help examiners identify the manufacturer, model and size of the footwear. Can be used to profile the suspect and provide leads on who may have bought or worn the footwear. • Approximate height: Investigators refer to statistical data to approximate the height of the person. Height can also be approximated by stride length.

22. Footprints • Activity of wearer: The footwear imprint left by a person is different when they are walking, running or carrying something. An impression left by a running person will be deeper in the heel and toe sections of the shoeprint. A person carrying a heavy load will cause deeper prints. • Link between a print and a piece of footwear: Every piece of footwear will show different amounts of tread wear and damage (tiny cuts and nicks).

23. Footprint impressions • When someone walks over soil, impressions are left in the ground. • To collect the evidence a frame is built around the print and suitable casting material poured in (usually plaster of Paris) and allowed to dry. • The cast is then removed and photographed.

24. How To Cast a Footprint • Place a ruler against the footprint and take a photograph of the footprint • Frame the footprint with four pieces of card or an aluminium frame • Apply fixant (hairspray) to help preserve detail. • Mix up the plaster and pour into the footprint impression. • Leave to harden and then remove cast • When hardened footprint is analysed- nicks, cuts and worn patterns are noted

25. Evidence Recovery • Lesson Objectives • All • To state the different techniques available for evidence recovery • Most • To describe each evidence recovery technique • Some • Identify the type of evidence that can be collected via each method.

26. Labelling evidence • A description of what the evidence is: e.g. 103 white tablets. • The exact location where it was found e.g. Oriel High School, Sc2, corner of teacher’s desk etc.. • The date and time when collected. • The name and signature of the person that collected it.

27. Soft Packaging Grip-seal bags Tamper evident bags Brown paper evidence bags

28. Hard Packaging Metal air tight tins Weapons tubes Cardboard evidence boxes

29. Activity 32.1F • You are a SOCO in charge of processing the scene of a drugs raid. The offender is suspected of producing and seller illegal drugs. • What types of evidence would you find at this crime scene? • How would you package each of the items recovered?

30. How is evidence collected?

31. Activity 32.1E Evidence Collection Techniques • You need to investigate the following techniques used to gather evidence: • Casting • Vacuuming • Hand picking • Swabbing

32. Marks and Impressions • Lesson Objectives • All • To state the different marks / impressions that could be recovered from a crime scene • Most • To describe how to collect evidence from different marks / impressions • Some • To explain what each of the different marks / impression can tell us

33. Tyre Prints • 3-D impression left by car wheels in cement, mud, sand, snow. • Recovered using plaster-casting

34. Tool marks • 3-D marks left in surfaces eg. Impressions made in surfaces from breaking in using a crowbar. • Recovered using putty-casting material.

35. Teeth marks • Tooth marks can be left in soft surfaces (apples, chocolate, skin). • Recovered using putty-casting.

36. Fingerprint marks • A fingerprint mark is a deposit of fatty residue left after sweat has evaporated. • The pattern within the deposit provides a mirror image of the ridges and troughs of the finger or palm.

37. Fingerprint marks There are 3 categories: • Latent - the most common type of print, invisible to the naked eye. Can be seen with powders. Recovered using taping. • Visible - resulting from fingers stained with a substance (ink, blood, dirt, mud, make-up). Recovered using taping. • Plastic - this is an impression made by the fingers on a soft surface (putty, Blu-tack, chocolate). Recovered using putty-type casting materials.

38. Lifting fingerprints • Put gloves on to prevent contamination • Dip the tips of the fingerprinting brush into powder to pick up a small amount. • Brush gently over the area to be treated taking care not to smear the print. Continue dusting lightly until the fingerprint develops. • Cut a piece of lifting tape about 7cm long. Press firmly over the print. Peel the tape from the surface in one smooth motion. • Place the tape onto a piece of acetate (lift card). Place in an evidence bag and label. • Prints are then compared with the national criminal records database for a match.

39. Forensic Case Study Activity • Research a infamous murder case eg The Soham Murders where Jessica Chapman and Holly Wells were killed by Ian Huntley. • Identify the types of evidence that the SOCOs would have looked for at the scene(s). • What were the health and safety issues associated with the crime scene(s)?