Crime Scene Investigation Flashcards
Recovery of samples
Liquids- clean swab
Dried- scraped or swabbed
Items- seized to lab. Not plastic or staples and seal immediately
DNA sources
Blood- minute needed Faeces- unlikely unless blood in it Hair- good with root Nasal secretions- can be good Salvia-good, most likely from cigarette ends, gags, envelopes, balaclava Semen- rich in DNA Skin- good if deep scratch to draw blood Swear- no cellular material Urine-unlikely Vaginal fluid- suitable
Recovery methods
Tape- record, use tweezers, two cuts only if bound, secure sticky side up in box with pin
Bottle/can- secure with ties in box. Swan if not taking
Clothing- brown paper bag, seal with tape. Dry wet clothes a on paper sheet
Blood - pipette in to plastic container or dry swab. If dry, take item, cut around or tape lift. Discard 1st meter. Seal between two pieces then envelope
Gum/cigarette - tweezer to container
Hair- keep clumps. Place on edge of tape
Document exams
Before fingerprinting
Techniques:
- physical- indentations, physical matching
- exam of printing processes and equipment
- detection of alterations, erasures, counterfeits and forgeries
- ink comparisons
- handwriting and signatures
Questioned document
Any document where the authenticity of all or part of the document is in dispute Or Where the source is unknown Or Which may have marks of evidential value
Specimen/comparison doc
Any material obtained from a proven source and used for comparison with a questioned doc
Latent indentations
Handwriting transfers to page physically beneath
To be done before fingerprints.
ESDA- electrostatic detection apparatus
Level of evidence - identification opinion
An opinion of identification is generally expressed with the wording:
The author of the specimen material completed (or didn’t) the questioned material
Level of evidence - qualified authorship opinion
There are indications the author of the specimen material completed (or did not) the questioned material
Conclusion accompanied by annex - for writing comparisons
Explains purpose of comparison
Outlines levels of opinion and reasoning
Provides info on validation and proficiency testing
Sending docs for exam
Brief report Descriptions of each Package questioned doc Unfold if necessary Seal airtight if wet, don't dry Put in sleeves and cardboard between Label before putting doc in
Plant/ mushroom at scene
Dry before envelopes Count plants Measure shortest, tallest and average 10 plants- leaf sample 11-20 - sample of 10 100+ - 50 leaf (at least 28g)
Computers at crime scene
Isolate from phone lines Determine if on or off and leave as is Photo if on Pull cord out of back first or battery out if laptop Collect removable storage and docs Look for written passwords/usernames etc
Fingerprints
Generic term used to describe the ridged skin in the undersides of the palms, fingers and feet or impression left by them
Left due to sweat pores when fridges contact surface. Known as latent print
Who and when can get FP
S32 - when in lawful custody and detained for committing offence and at police station
S33 - can detain for FP if going to summons
S34 - destruct FP if charges dropped or acquitted
FP forms
Elimination prints pol378
Voluntary prints pol545
Reconnaissance
Prelim inspection or survey made to get an overall picture of scene without disturbing evidence Allows for: Prelim reconstruction Appreciation Plan of action
Reconstruction
A theory about what took place in a given area over a relevant period of time and how it is likely to have happened. Formed by logically piecing together all info gained from exam and enquiry
Searching scenes
Grid
Lane
Spiral - start central
Zone
Decontamination zones
Hot - part requiring exam and evidence collection
Warm - transition zone to enable examiners to put on and take off protective clothing, access equipment , process exhibits etc
Cold - within outer cordon for meetings, meals, scene guards etc
Log movements between zones
Admissible
Allowable evidence accepted by the court.
Exhibit must have relevance and just be able to demonstrate reliability through integrity of chain of evidence
Blood stain pattern analysis
Pool - lying in position for extended period Dripped - direction and movement Spattered - impact or blows Arterial spurting - injury type Back spatter - firearm wound
Contamination
When material is added to exhibit post incident
Cross contamination
Occurs through the exchange of traces of forensic material between offender, scene, victim and other people.
Example- same vehicle transport
Entomological samples
Insect samples collected from scene that can assist objective evidence such as estimated time of death
Latent samples
Hidden or concealed
I.e not present to human eye but revealed with powder, chemicals or lighting
Integrity of evidence protected through
Controlling access and documenting
Exams done by trained or qualified
Chain of evidence secure
Tested when presented in court
Order of exam
Preferred sequence of exam or analysis
Persistence
Length of time forensic material is able to be detected following a crime
Primary transfer
Direct transfer of forensic material from one party to another. Generally requires contact.
Secondary transfer
Indirect transfer of evidence to third party
Ie Male a fibre on to women. Women to Male b. No contact between a and b
Significance
Evidential value of material sample for the evidence collection. Important in decision making about what samples for analysis
Trace evidence
Microscopic or minute samples of evidence
