Processing the Crime SceneCSP

What does it involve?

• the sequence of events by which all evidence at a scene is located, recorded and collected

Exercise 3.1• size of scene• number of pieces of evidence• number of CS officers (importance of case)• difficulty in finding evidence• difficulty in collecting evidence

Steps involved

• initial photography• sketching the scene• searching for evidence• documenting the location of evidence• collecting and preserving evidence

Sketching the crime scene

• must be done at the scene• does not have to be beautiful or perfect• representation of the basic layout of the important aspects of the scene

Exercise 3.2• shape and dimensions of crime scene• location of fixed items within scene• location of evidence

• draw the basic outline and mark important measurements• the main sketch will be a floor/ground plan: bird’s eye view• add fixed scene items:• indoor: doors, windows, furniture• outdoor: roads, creeks, buildings

• add evidence (use letters for small items)• features above ground/floor level will need a separate sketch (elevation

view)• locate small items on the sketch by triangulation

Exercise 3.3• 3.2 – shape, furniture• 3.3 - roads

A1200

875

Searching

Give examples of physical evidence that is:(a) hidden• something inside a drawer, box, underwater

(b) very small• hair, fibre

(c) invisible• smell, vapour

Give examples of non-physical evidence that can be observed during the search of a crime scene?• doors open/closed, lights on/off

Why are these qualities important?Attention• don’t miss anything

Patience• you will have to spend a lot of time of time looking at “nothing” to find

the important items System • you will miss the “bits in between”

A search should not: • disturb evidence before it is recorded, and • contaminate or destroy evidence

Numbered markers:• put down near the evidence• clearly indicate its presence• help identify that evidence in the documentation (photographic and

written)

All items are recorded on a Evidence Log:• tag number• item description• person who found it (if more than one involved in the search)• other information

Documenting a crime scene

• written notes (by hand or on computer)• still photographs • video

EXERCISE 3.6What extra value in documenting the processing of the crime scene is provided by:(a) still photographs• show details which are too hard to describe in words

(b) video• provides “walk through” capability

(c) written notes• some things can’t be photographed

Written notes

• made at the time that events occur, not afterwards• made in chronological order• detail all actions• complete and thorough• clearly and legibly written• record unexpected or negative conditions (e.g. lack of blood around victim,

no signs of forced entry, lights on/off)• be specific• record the relevant • leave fine detail to photography

Types of photographs

• overall – these provide a basic overview of the layout of the scene• unlikely that one single photo will be able to cover the entire scene• Ex 3-7 Why can’t one overall photo cover even a small room?• it can’t include the wall in line with you

• evidence-establishing – these demonstrate the location of items of evidence relative to the recognisable parts of the scene (eg walls, furniture, trees, cars)• use of numbered “labels” to help pinpoint evidence and link it to log

• evidence-closeup - record the presence and appearance of the physical evidence• the item must fill the frame of the photo to provide maximum detail

EXERCISE 3.8• How would you take the closeup photo for the evidence in Figure 3.5 so that

the scale is evident?• someone else needs to hold the scale near the blood spatter • don’t stick it to the box

• EXERCISE 3.9• Assume you are required to photograph a house that has been burgled.

What photographs of each type should you take?• Overall:• exterior of house showing point of entry• any rooms where evidence is expected

• Establishing – showing location of evidence• Closeup – each piece of evidence

Collection and preservation of evidence

• done after the scene is thoroughly documented• most fragile or most easily lost evidence collected first• it may be collected before the whole scene is searched and documented

if considered likely to be lost

Exercise 3.10(a) What types of evidence are the most fragile/easily lost?• fingerprints (and other types of prints)• almost anything outdoors if the weather is bad(b) What types of evidence might need to be moved?• bodies• dangerous substances

General rules for evidence collection

• most evidence - paper containers such as packets, envelopes, and bags• liquid items - non-breakable, leakproof containers.• arson evidence - air-tight, clean metal cans• large quantities of dry powder - plastic bags• moist or wet evidence, eg blood, plants• temporarily in plastic containers • back at the “office” - completely air dry• the repackaged in a new, dry paper container

General rules for evidence collection

• any items which may cross contaminate each other must be packaged separately

• the “containers” should be closed and secured to prevent the mixture of evidence during transportation

• each “container” should have:• a unique identifying code number• the collecting person's initials• the date and time it was collected• a description of the contents• the case report number

Value of evidence

• some evidence is more useful than others• it should be dealt with first

EXERCISE 3.11Why are fingerprints a more valuable piece of evidence than fibres, pieces of glass etc?• fingerprints, if good, are unique• fibres and glass can occur in many locations• cannot definitely link suspect to scene

EXERCISE 3.12

Give examples of items of evidence likely to have bodily fluids on them that:• could be transported back to the lab• clothing• weapons• vehicles• could not be transported back to the lab• fixed parts of buildings• ground, eg grass, paving

Other collection issues

• firearms on TV shows vs reality• double bagging of trace items – why?• too easily lost from single packet

Presumptive tests

• identification of whether an item is actually relevantExercise 3.13Why are these important?• quick • to be useful on site• simple• to be useful on site• sensitive• minimise amount of evidence consumed• provide a visual result• no extra equipment required

False positives

• few presumptive test are totally specific• can give a positive test for materials other than the intended one• known as a false positive

Exercise 3.14Given false positives, what conclusion can you draw from:• a positive test• could be relevant evidence

• a negative test• very unlikely to be relevant evidence

• Do you think this limitation is a problem?• no• better to take much back to the lab than leave real evidence behind

Latent fingerprints

1. finding them2. making them visible3. recording or transporting them

EXERCISE 3.15Why is contrast required for dusting powders?• step 2 above