Evidence and It's Importance Unit 3 Creative Project Elizabeth Hall Kaplan University CJ210 Criminal Investigation Joseph Reynolds November 3 2009 Gathering Fingerprint Evidence
What are the main types of evidence, and what is their importance to the investigative process?
Crime Scene Tool Kit
Types of Evidence, and the Techniques Used for Collection
Evidence is predominantly grouped into two categories which can then be broken down into subgroups:
Physical Evidence also known as "real evidence.- "Locard's Exchange Theory: every
contact leaves a trace". (DNA Initiative, 2008)
Testimonial Evidence is statements, or oral facts given to investigators by witnesses, informants, or victims.
Evidence Collection ID Tag
Types of Evidence, and the Techniques Used for Collection Continued
Fingerprints- Collected with a variety of tapes, powders, chemicals, and glues using the contrast technique.
Firearms- Bullet casings, striation marks and spent cartridges, these are collected with tweezers and sealed in an evidence container
Trace Evidence- Hairs, fibers, and particulate material, collected by shaking, sifting, tape lifting, or vacuuming.
Fingerprint- Green Magnetic Powder
Types of Evidence, and the Techniques Used for Collection Continued 2
Physical Evidence 2
Document evidence- Letters, papers, handwriting samples collected, and sealed in evidence containers
Physical evidence, properly collected, documented, and analyzed is:
more reliable than testimonial evidence,
known as the silent witness
can corroborate witness statements
help investigators reconstruct the crime
is completely objective
can help to prove or disprove innocence. (DNA Initiative. (2008))
Biological Specimen Kit
Types of Evidence, and the Techniques Used for Collection Continued 3
Testimonial evidence includes signed statements, videos, and audio recordings.
Can be gathered in various places, for example: the police station, a person's home, a hospital, or anywhere an officer can talk to or ask a person questions.
Is collected with the use of paper, pens, video equipment, or audio equipment.
Photographic Barrier Filter
Once evidence is collected, it must be developed and examined using various types of equipment and chemicals.
Fingerprints-developed and examined using the contrast method, and fuming methods, comparison to known prints, and fingerprint microscopes.
Firearms and tool striations- developed and examined using morphology, spectrophotometers, mass spectrographs, and various magnifying instruments
Trace Evidence- developed and examined using tapes, filters, spectrometers, high resolution lenses, various microscopes, spectrographs, x-ray diffraction, neutron activation, and chromatography instruments
Cyanoacrylate Fuming Chamber
Evidence Examination 2
Biological evidence is developed and examined in different ways depending on the material
DNA- short tandem repeat (STR) testing
Blood- Leuco-Malachite Green Test, Luminol,
Reduced Phenolphthalein Test, Tetramethyl
Benzidine Test, Hemin Crystal Test, Precipitin
Test, Blood Group Test, and DNA tests, Spatter Trajectory Tests
Biological evidence can definitively tie a suspect to a crime, since no two person's DNA is the same with the exception of some twins.
Blood Spatter Tool Kit
Evidence Examination 3
Document Evidence is developed and examined in numerous ways, by experts in forgery, handwriting, fingerprints, paper, and ink, using fuming, microscopes, magnifiers, chemicals, spectrometers, chromatographs, and spectrophotometers
Testimonial evidence is examined with polygraph tests, voice analysis, body language, and the skills developed by the investigator.
Fingerprints-Check developed with Ninhydrin
Information from Evidence
Information found through investigation can:
"Identify a substance, object, or instrument"
Fingerprints- can definitively identify a suspect, and place them at the scene of the crime because no two people have the same fingerprint whirls, arches, loops, dots, ridge endings, bifurcations, short ridges, enclosures, bridges, spurs, or trifurcation ridge endings
Firearms, shoes, and tools develop individualized striations from use or manufacture that can positively identify them as being at the scene, or help to reconstruct the scene using morphology
The rules of Locard's Law applies to everyone, not just suspects, victims and witnesses
Environmental issues such as rain, heat, wind can contaminate or cause the evidence to erode, deteriorate, or disappear
For witness corroboration, people can forget details
Too many people in the crime scene area
Improper packaging or storage
Tamper Resistant Evidence Bag
Relevant Issues The sciences of evidence have come a long way in a few short years. While there are still issues concerning the reliability of the science behind the results, the advanced use of science has proved to be an invaluable tool in the protection of those who are innocent Wheel used to mark off crime scene
The DNA Initiative. (2008). Crime Scene and DNA Basics for Forensic Analysis Retrieved from the World Wide Web
October 30, 2009 http://dna.gov/training/evidence
Evident Crime Scene Products (2009) Quality Products Delivered. Retrieved from the World Wide Web October 30, 2009. http://www.evidentcrimescene.com/cata/photo/photo.html