Name 6 types of common physical evidence types, and describe them all as well. (*Remember, you only need to know 5! Just play it safe and know 6!!!)
1. Paint- Any paint, liquid or dried, that may have been transferred from the surface of one object to another during the commission of a crime. A common example is the transfer of paint from one vehicle to another during an automobile collision.
2. Hair- Any animal or human hair present that could link a person with a crime.
3. Fingerprints- All prints of this nature, hidden (latent) and visible.
4. Fibers- Any natural or synthetic fiber whose transfer may have be useful in establishing a relationship between objects and/or people.
5. Drugs- Any substance seized in violation of laws regulating the sale, manufacture, distribution, and use of drugs.
6. Powder Residues- Any item suspected of containing powder residues resulting from the discharge of a firearm.
-The process of determining a substance's physical or chemical identity.
-The process of ascertaining whether two or more objects have a common origin.
-A formula for determining how frequently a certain combination of characteristics occurs in a population. The product rule states that one must first determine the probability of each characteristic occurring separately, the multiply together the frequencies of all independently occurring characteristics. The result is the overall frequency of occurrence for that particular combination of characteristics.
-The frequency of occurrence of an event.
-Properties of evidence that can be attributed to a common source with an extremely high degree of certainty.
-Properties of evidence that can be associated only with a group and never with a single source.
Physical Evidence is usually examined by a forensic scientist for....
identification or comparison
Forensic Comparison is a two-step procedure... name the two steps!
1. Combinations of select properties are chosen from the suspect and the standard/reference specimen for comparison.
2. Once the examination has been completed, the forensic scientist must draw a conclusion about the origins of the specimens.
Name some examples of individual characteristics...
- -the matching ridge characteristics of two fingerprints
- -the comparison of random striations (markings) on bullets or tool marks
- -the comparison of irregular and random wear patterns in tire or footwear impressions
- -the comparison of handwriting characteristics
What is one disappointment awaiting the investigator unfamiliar with the limitations of forensic science...
the frequent inability of the laboratory to relate physical evidence to a common origin with a high degree of certainty.
Tell me, what is the Integrated Automated Fingerprint Identification System?
*Plus, who maintains it?
- -A national fingerprint and criminal history system maintained by the FBI and launched in 1999.
- *Contains fingerprints corresponding criminal history information for nearly 50 million suspects (or 500 million fingerprint images), which are submitted voluntarily to the FBI by state, local, and federal law enforcement agencies.
-Tell me, what is the Combined DNA Index System?
*Plus who maintains it?
- -The FBI's Combined DNA Index System became fully operational. CODIS enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles, thereby linking crimes to each other and to convicted offenders.
CODIS creates investigative leads from two sources: ...what are they?
the forensic index and the offender index
What is the world's first national DNA database?
The United Kingdom's National DNA Database
-The method used to support a likely sequence of events at a crime scene by observing and evaluating physical evidence and statements made by those involved with the incident.
-Tell me, what is the National Integrated Ballistics Information Network?
*Plus who maintains it?
- -Maintained by the Bureau of Alcohol, Tobacco, Firearms and Explosives, allows firearms, analysts to acquire, digitalize, and compare markings made by a firearm on bullets and cartridge casings recovered from crime scenes.
So, the heart of NIBIN is the Integrated Ballistic Identification System (IBIS), comprising...
a microscope and a computer unit that can capture an image of a bullet or cartridge casing. The images are then forwarded to a regional server, where they are stored and correlated against other images in the regional database. IBIS does not positively match bullets or casings fired from the same weapon; this must be done by a firearms examiner by producing a short list of candidates for the examiner to manually compare.