Other stuff Flashcards
What does OSAC stand for?
Organization of Scientific Area Committees
What does PCAST stand for?
President’s Council of Advisors on Science and Technology
What type of camera do you use and how many megapixels is it?
I am currently using the Z5 and it is 24.3 MP
What does JPEG stand for?
Joint Photographic Experts Group
Can you name any critics of friction ridge identification?
Simon Cole published Suspect Identities which calls in to question the validity of fingerprint identification as a scientific process and brings up its’ troubling history in Western society as it relates to eugenics (GALTON).
Have errors occurred in your discipline?
Yes we do not claim a zero error rate. A study published in the Proceedings of the National Academy of Sciences involving many fingerprint experts found the rates of error were: 0.1% for false positives and 7.5% false negatives. Both without verification.
What does IAI stand for
International Association for Identification - The oldest and largest forensic association in the world.
What is a recent article or book that you’ve read
I read an article called ‘Thinking outside the (glove) box’ in the Journal of Forensic Identification by Nora RAJS and others. The article was about the best methods for developing fingerprints on latex gloves and it concluded that a combination of Ninhydrin and CA yielded the best results.
What is Stokes shift
The difference between the lavelength at which a molecule emits light and the wavelength at which it absorbs light.
How can you determine the direction of travel of a vehicle based on the tiretracks?
- The front tires turn and the rear tires are always straight.
- If the vehicle went over grass or other plants, direction can be determined based on which way the growth is flattened
- spatter from spinning tires
- Some tires are directional, whichever way the tip of the triangular features point is the front of the vehicle.
- Occasionally details from the sidewall might transfer. Sidewalls on a directional tire have an arrow showing the front.
Name 8 components of tire tread
-Wear bar indicators
-Groove
-Lateral grooves
-Notches
-Rib
-Rib element
-Sipes
-Tread width
What is silver nitrate used for and what does it react with?
Silver Nitrate is a development method for fingerprints and it reacts with salt in the sweat
Which countries use a numeric system for fingerprint identification?
Most European and South American countries use a numeric standard. Italy, Spain, Hungary, Portugal, Poland ect…
Who was the first to propose rules establishing the minimum number of minutiea necessary for an identification?
Edmond Locard in 1914. The Tripartite rule:
- 12 + points identity is beyond debate
- 8-12 Borderline and depends on teh sharpness and rarity
- Less than 8 than there is no certainty to the identificaion
What is a white box study?
A white box study looks at the entire process and not just the outcome or opinion.
What two black box studies validate fingerprint identification?
1) FBI Noblis black box study - False Positive 0.1% and False negative 7.5%
2) Palm print black box study Eldridge and Forensic Science international - false positive 0.4% and False negative 9.5%
What does LASER stand for?
Light Amplified by the Stimulated Emission of Radiation
What is the inverse square law as it relates to photography?
The observed intensity of light is inversely proportional to the square of the distance from the source (flash)
Explain the gold zinc vacuum metal deposition fingerprint development method?
VMD is an extremely sensitive process involving thermal evaporation and deposition of thin metal films under high vacuum conditions. VMD targets fats, amino acids, and eccrine substances within a fingerprint matrix. Exhibits are attached to a support/tray with no overlap. The chamber is sealed (air tight) and a very low vacuum is created. Two metals are sequentially evaporated: the 1st metal, typically gold, deposits a thin layer across the surface and is absorbed by the fingermark matrix; the 2nd metal, typically zinc, deposits a thin layer only where gold was deposited. Friction ridges remain the color of the substrate, while the background and furrows appear gray. Other metals such as silver, sterling silver, and copper can also be used. Gold/zinc provides excellent clarity and contrast on a wide range of surfaces.
What methods are available to develop friction ridge impressions on previously wetted paper exhibits?
Articles must be thoroughly dried first.
1- fluorescence examination
2- Physical Developer.
The Home Office Fingerprint Development Techniques Manual does not recommend VMD on porous objects; however, CPC slide notes indicate that VMD can be used on porous substrates and articles that have previously been wetted. Oil Red O is also mentioned as an option.
What does Indanedione react to?
Indandione reacts with amino acids.
Why are DFO and Ninhydrin capable of developing old friction ridge impressions?
DFO and ninhydrin are highly sensitive to amino acids in latent impressions and amino-containing compounds (mainly proteins) in blood. The amino acids are relatively stable over time, unlike fats, grease, or oils in the fingerprint impression which degrade more quickly.
What techniques could you use to develop friction ridge impressions on skin?
On smooth areas of dry skin, fingerprints contaminated with oil or grease may be developed using powders or fluorescence examination. For fingerprints on skin in blood, techniques include iodine followed by transfer onto a silver plate, transfer onto glazed art paper (kromecote) followed by dusting with conventional powders, magnetic powder followed by transfer onto dactyl-foil, and cyanoacrylate. The Home Office fingerprint manual also mentions lead dust followed by x-ray imaging.
Radial loops are commonly found on which finger?
85% of radial loops are found on the index finger.
What is a control sample and why might it be necessary to collect such a sample?
Control samples are collected to ensure that the materials used for analysis are not reacting with the control materials. This helps ensure that any observed changes or results are due to the variables being tested, not unintended interactions with the control material. In DNA or blood collection, the control sample would be a swab from the same package as the swab used for collection or the sterile liquid that was used to wet the swab.
What is the inverse square law as it refers to light?
The inverse square law states that the intensity of light reaching an object is inversely proportional to the square of the distance between the object and the light source.
What is luminescence?
Luminescence is a spontaneous emission of light by a substance not resulting from heat. Examples include: bioluminescence (light from biological processes, e.g., fireflies), chemiluminescence (light from chemical processes, e.g., luminol/blue star), phosphorescence (light emitted after excitation, e.g., glowing stickers), and fluorescence (light emitted during excitation).
What are some of the databases that are searched when DNA is sent to the lab?
The National DNA Databank, maintained by the RCMP contains the following Indices:
Convicted Offenders Index
Crime Scene Index
Victims Index
Voluntary Donors Index
Missing Persons Index
Relatives of Missing Persons Index
Human Remains Index
CODIS is the American version of the NDNA DB which also gets searched
