Chapter review 1-3

Suspected Ricin attack! Investigators are trying to track the substance to its source. Which forensic tests should be done on the envelopes?

*Fingerprints may be detectable on paper using a variety of chemical developing techniques • Paper examination may identify a manufacturer: appearance, watermarks, fiber analysis, and chemical analysis of pigments, additives, and fillers may reveal paper's origin • DNA may be recovered from saliva residues on the back of a stamp or on envelope glue • Typescript comparison of transient defects from printing plates impacting the envelope • Ink analysis may reveal a pen's manufacturer • Trace evidence, such as hairs and fibers, may be present within the contents of the envelope • Indented writing may be deposited on paper left underneath a sheet of paper being written upon. • Handwriting examination to compare writing on several envelopes • Cellophane tape may have been used to seal envelope. Examining ends may determine where tape came from

The following are three possible combinations of DNA characteristics that may be found in an individual's genetic profile. Using the product rule, rank each of these combinations of DNA characteristics from most common to least common. The number after each characteristic indicates its percentage distribution in the population. A. FGA 24, 24 (3.6%), TH01 6,8 (8.1%), and D16S539 11,12 (8.9%) B. vWA 14,19 (6.2%), D21S11 30,30 (3.9%), and D13S317 12,12 (8.5%) C. CSF1PO 9,10 (11.2%), D18S51 14,17 (2.8%), and D8S1179 17,18 (6.7%)

Product Rule: A, C, B

An investigator at a murder scene notes signs of a prolonged struggle between the attacker and victim. Name at least three types of physical evidence for which the investigator would probably collect standard/reference samples, and explain why he or she would collect them.

An investigator would likely collect standard/reference samples of hair, fibers, and buccal swabs for DNA profiling, because these items are most likely to have been involved in a cross-transfer during a long struggle

Arrange the following tasks in order from the one that would require the least extensive testing procedure to the one that would require the most extensive. Explain your answer. A. Determining whether an unknown substance contains an illicit drug. B. Determining the composition of an unknown substance C. Determining whether an unknown substance contains heroin

C. Determining whether an unknown substance contains heroin would require the least extensive testing, because the investigator can select only procedures designed to detect the presence of heroin. A. Determining whether an unknown substance contains an illicit drug would require the next most extensive testing regime, because the investigator must select as many procedures as necessary to test for all types of illicit drugs. B. Determining the composition of an unknown substance would likely require the most extensive testing, because of the extremely large number of possible substances to test for.

For each of the following pieces of evidence, indicate whether the item is more likely to possess class or individual characteristics • An impression from a new car tire • A fingerprint • A spent bullet cartridge • A mass-produced synthetic fiber • Pieces of a shredded document • Commercial potting soil • Skin and hair scrapings • Pieces of multilayer custom car paint

Class Individual Individual Class Individual Class Individual Individual

What kind of search pattern(s) would investigators be most likely to employ when two people are searching a small area with well defined boundaries.

Grid Search or Line Search

What kind of search pattern(s) would investigators be most likely to employ when several people are searching a large area.

Quadrant (Zone) Search

Evidence with individual characteristics can lead to a determination of common origin. Which type of evidence CANNOT yield such results?

Single-layer paints

What kind of search pattern(s) would investigators be most likely to employ when one person is searching a large area.

Spiral Search or Line Search

What are the guidelines that the court offers that one must follow when determining the admissibility?

The court offers 5 guidelines: • Scientific technique can or has to be tested • Technique has been subjected to peer review and publication • Technique's potential error rate • Existence of standards • Whether technique is accepted in scientific community

Whose responsibility is it to decide the admissibility and reliability of scientific evidence presented in court?

The judge is considered the "gatekeeper."

Evidence associated with a group and not with a single source is said to possess ___________characteristics

class

A(n) ____________ analysis subjects a suspect specimen and a standard/reference specimen to the same tests and examination in order to determine whether they have a common origin.

comparative

The number and type of tests needed to identify a substance must be sufficient to____________ all other substances from consideration.

exclude

Which of the following is NOT true? An expert witness must be able to demonstrate

formal degree in forensic science

The process of ____________ determines a substance's physical or chemical identity with as near absolute certainty as existing analytical techniques will permit.

identification

Evidence that can be traced to a common source with an extremely high degree of probability is said to possess ____________characteristics.

individual

An officer is the first responder to an apparent homicide scene. After securing the area, interviewing the sole witness, and calling for backup, he begins to search for evidence. He makes note of a bloody knife lying next to the body, with a small scrap of bloody cloth clinging precariously to the knife. Because it is a very windy day, the officer removes the scrap of fabric and seals it in a plastic bag. A few moments later, a crime scene team, including a photographer, arrives to take over the investigation. What mistakes, if any, did the Officer make before the crime-scene team arrived?

• Officer should not have removed the scrap of cloth until the photographer had arrived and taken a picture of the evidence. • He also should have put on latex gloves or used forceps or another tool to remove the scrap of cloth. • Finally, he should have placed the cloth in a paper bag or other container where air could circulate, rather than in a sealed plastic bag where moisture could accumulate and cause mold to grow on the cloth.

You are the first officer at the scene of an outdoor assault. You find the victim bleeding but conscious, with two of the victim's friends and several onlookers standing nearby. You call for backup and quickly glance around but see no one fleeing the scene. Describe the steps you would take while you wait for backup to arrive.

• Summon medical assistance for the victim • Detain any suspects at the scene • Establish boundaries of the crime scene • Ensure no unauthorized personnel enter the crime scene