Forensics Chapter 2

Three methods for recording the crime scene are ____, ____, and ____

photography, sketches, notes

The term ____ encompasses all objects that can establish whether a crime has been committed or can link a crime and its victim or its perpetrator.

physical evidence

standard/refernece sample

physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime scene evidence

finished sketch

precise rendering of the crime scene, usually drawn to scale

An investigator need only draw a(n) ____ sketch at the crime scene to show its dimensions and pertinent objects.

rough

Each item collected at the crime scene must be placed in a(n) ______ container.

separate

Most physical evidence collected at the crime site will require the accompanying submission of ____ material for comparison purposes.

standard reference

A detailed search of the crime scene for physical evidence must be conducted in a(n) _____ manner.

systematic

All unauthorized personnel must be ____ from crime scenes.

taken away

physical evidence may be obtained from...?

the crime scene, the victim, and the suspect

the obligation to maintain the integrity of evidence belongs to who?

the evidence clerk

autopsy

the medial direction and examination of a body in order to determine the cause of death

the manner of collecting and preserving physical evidence at a crime scene is determined by what?

the nature of the evidence

List at least four pieces of evidence from a murder scene that must be collected a sent to the forensic laboratory. Why must these items be collected at the crime scene instead of later?

the victims clothing; fingernail scrapings; head and pubic hairs; blood for DNA typing; vaginal, anal, and oral swabs in sex related crimes; recovered bullets from the body; and hand swabs from shooting victims. These items must be collected at the autopsy because once the body is buried, efforts at obtaining them may prove difficult or futile. Also a lengthy delay in obtaining many of these items will diminish or destroy their forensic value.

the relative evidential value of laboratory test results is almost always dependent on what?

the way the evidence is collected and presented for examination

True or False: One method for approximating the time of death is to determine body temperature.

true

The most important prerequisite for photographing a crime scene is to have it in a(n) _____ condition.

unaltered

substrate control

uncontaminated surface material close to an area where physical evidence has been deposited; used to ensure that the surface on which a sample has been deposited does not interfere with laboratory tests

in cooperation with the medical examiner or coroner, what type of evidence is to be retrieved from a deceased victim for examination in the crime laboratory?

victim's clothing fingernail scrapings head and pubic hairs blood (for DNA purposes) vaginal, anal, and oral swabs (sex-related cases) recovered bullets from body hand swabs from shooting victims (gunshot residue analysis)

Describe a druggist's fold and explain why it is a better way to store trace evidence than an ordinary mailing envelope.

A druggist fold consists of folding one end of a piece of paper over one-third, then folding the other end over that, and repeating the process from the other two sides. After the paper is folded in the manner the outside two edges are tucked into each other to produce a closed container that keeps the specimen from falling out. The druggist fold is a better way to store evidence than an ordinary mailing envelope because powders and fine particles will leak out of the corners of an envelope.

What does a forensic entomologist study to estimate time of death? Explain why such estimates are not always straightforward.

A forensic entomologist studies the development of insect larvae in a body to estimate time of death. These determinations are nt alwad straightforward because the rate at which the larvae develop is affected by environmental influences such as geographical location, climate, and weather conditions.

Name and describe the two kinds of sketches prepared for a crime-scene.

A rough sketch is a draft representation of all essential information and measurements, and is drawn at the crime scene. A finished sketch is a precise rendering of the crime scene, usually drawn to scale

What is a standard/reference sample? Why is collecting such a sample important to the crime-scene investigator?

A standard/reference is an item of physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence. The quality and quantity of standard/reference specimens often determine the evidential value of crime-scene evidence.

What is a substrate control and how is it used by the crime-scene investigator?

A substrate control is uncontaminated surface material close to an area where physical evidence has been deposited. This sample is used to ensure that the surface on which a sample had been deposited does not interfere with laboratory tests.

In what situations is an autopsy typically performed?

An autopsy is usually preformed if the cause of death is suspicious or unexplained.

What is chain of custody and why is it important to maintain chain of custody?

Chain of custody is a list of all people who came into possession of an item of evidence. Failure to substantiate the chain of custody may lead to serious questions regarding the authenticity and integrity of the evidence and the examinations of it.

Name one type of evidence that should be stored in an airtight container and one type that shouldn't be. Explain why each type of evidence should or should not be stored in this way.

Charred debris from the scene of a suspicious fire must be sealed in an airtight container to prevent evaporation of volatile petroleum residues. Items of clothing found at a crime scene should be air-dried and placed individually in separate paper bags to ensure constant circulation of air through them and thus prevent the formation of mold and mildew.

What method is not used to approximate time of death?

Loss of body mass

If objects have been moved or removed from a crime scene, the investigator should...

Note that the objects were moved, but do not reintroduce them to the crime scene.

Name three methods for recording a crime scene and list one unique advantage of each.

Photography: advantage-unsurpassed in the definition of detail it provides. Sketches: advantage-record precise distances between important points in the crime scene. Notes: advantage- provide a source of detailed information about the scene for future reference.

What is physical evidence? Give three examples of physical evidence that might be found at a crime scene.

Physical evidence encompasses any and all objects that can establish that a crime has been committed or can link a crime an it's victim or it's perpetrator. Examples include hair, skin, fibers, fingerprints, blood, DNA, weapons, soil, glass, and documents.

What is the most important consideration when handling and processing physical evidence?

Physical evidence must be handled and processed in a way that prevents any change from taking place between the time it is removed from the crime scene and the time it is received by the crime laboratory.

Define the terms rigor mortis, livor mortis, And algor mortis and explain how they are important to a forensic pathologist.

Rigor mortis is a medical condition that occurs after death and results in the stiffening of body parts in the position they are in when death occurs. Livor mortis is a medical condition that occurs after death and results in the settling of blood in areas of the body closest to the ground. Algor mortis refers to postmorem changes that cause a body to lose heat. They are important to the forensic pathologist because they offer several ways to approximate the time of death.

What areas should be photographed during a crime-scene investigation?

The areas photographed should include the location in which the crime actually took place and all adjacent areas where important acts occurred immediately before or after the commission of the crime.

What is the first step in processing a crime scene?

The first step is to secure and isolate the scene.

What is the best way to maintain the integrity of physical evidence?

The integrity of evidence is best maintained when the item is kept in its original condition as found at the crime site.

Why should all items of evidence be placed in separate containers?

To prevent damage through contact and cross-contamination

Describe the best way for an investigator to handle trace evidence found on articles collected at the crime scene. Name two exceptions to this general rule.

Trace evidence should not normally be removed from articles at a crime scene. Instead the entire object should be sent to the laboratory for processing. If evidence is adhering to an object in a precarious manner, however, it should be removed and packaged. If evidence is found adhering to a large structure, such as a door, walk, or floor, it should be removed with a forceps or other appropriate tool.

chain of custody

a list of all people who came into possession of an item of evidence

livor mortis

a medical condition that occurs after death and results in the setting of blood in areas of the body closest to the ground

rigor mortis

a medical condition that occurs after death and results in the stiffening of a muscle mass; the rigidity of the body begins within 24 hours of death and disappears within 36 hours of death

algor mortis

a process that occurs after death in which the body temperature continually cools until it teaches the ambient or room temperature

rough sketch

a sketch, drawn at the crime scene that contains an accurate depiction of the dimensions of the scene and shows the location of all objects having a bearing on the case

buccal swab

a swab of the inner cheek, performed to collect cells for use in determining the DNA profile of an individual

As a matter of routine, all items of clothing are to be ____ before packaging.

air dried

physical evidence

any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator

what items may NOT be placed in an airtight container?

bloodstained clothing

Besides the more obvious items of physical evidence, possible ____ of trace evidence must be collected for detailed examination in the laboratory

carriers

The possibility of future legal proceedings requires that a(n) _____ be established with respect to the possession and location of physical evidence.

chain of custody

what items may be placed in an airtight container?

charred debris recovered from fire, glass, hairs and fibers, explosive residues

Photographs of physical evidence must include overviews as well as ____ to record the details of objects.

close ups

Name three factors that influence how an investigator conducts a crime scene.

depends on the locale, the size of the area, and the actions of the suspect(s) and victim(s) at the scene.

the evidence collector is not concerned with...

determining the natural variations that exist in physical evidence

True or false: An ordinary mailing envelope is considered a good general-purpose evidence container.

false

True or false: Charred debris recovered from the scene of an arson is best placed in a porous container.

false

True or false: Scientific evaluation of crime-scene evidence can usually overcome the results of a poorly conducted criminal investigation.

false

True or false: The techniques of physical evidence collection require a highly skilled individual who mist specialize in this area of investigation.

false

An airtight container (is, is not) recommended packaging material for blood-stained container.

is not

Whenever possible, trace evidence (is, is not) to be removed from the object that bears it.

is not

When ____ sets in after death, the skin appears dark blue or purple in areas closest to the ground.

liver mortis

the evidence collector is concerned with...

maintaining the chain of custody, utilizing the proper packaging material for evidence, labeling evidence, collecting control specimens

What information must be included in written notes made at the crime scene?

must include a detailed written description of the scene with the location of items of physical evidence recovered; the time an item of physical evidence was discovered; by whom, how, and by whom it was packaged and marked; and the disposition of the item after it was collected.

Why is it important to exclude onlookers from a crime scene?

Every individual who enters the scene had the potential To destroy physical evidence. No tampering of evidence and any contamination

What is an example of substrate control?

Floorboards from an arson scene that contain no trace of accelerants.

What is the most important prerequisite for photographing a crime scene?

For it not to be altered.

What is forensic anthropology? List two ways in which a forensic anthropologist might identify a victim.

Forensic anthropology is concerned primarily with identifying and examining human skeletal remains. A forensic anthropologist might identify a victim by examining bones for specific characteristics, such as sex, age, race, or traces of injury. A forensic anthropologist might also identify a victim by creating a facial reconstruction.

In cooperation with the medical examiner or coroner, evidence retrieved from a deceased victim to be submitted to the crime laboratory should include _____, _____, _____, _____, _____, ______, and _____.

Clothing fingernail scrapings head and pubic hair blood vaginal, anal, and oral swabs bullets hand swabs