Forensic Science Chapter 2

paper bindle

a folded paper used to hold trace evidence

indirect evidence that can be used to imply a fact but that does not directly prove it

distinguish between direct and circumstantial evidence

Requirements of a Forensic Investigator

must be able to identify the evidence, record it, and determine its significance. collect all evidence.

Detectives

interview witnesses and share information with crime scene investigators

Protective gear

latex gloves, shoe covers, overalls, mask/goggles, biohazard bag for infectious and blood-soaking objects

safety of individuals and preservation of evidence

explain the importance of securing the crime scene

This process ensures that the evidence has been responsibly handled as it was passed from the crime scene to a courtroom

explain the importance of the chain of custody of evidence

Direct Evidence

first hand observations: eye witness accounts, police dashboard video cameras, confessions

.class evidence material that connects an individual or thing to a certain group individual evidence evidence that identifies a kind of particular person or thing

compare and contrast class evidence and individual evidence

Unlike what television CSI programs portray, forensic lab technicians are specialized and process one type of evidence.

contrast the evidence examiners on television programs such as CSI with real life evidence examiners

.

describe each of the various search patters spiral grid, linear, quadrant

.police, crime scene investigators, medical examiners, detectives, specialists

describe the types of professionals who are present at a crime scene

Reference sample

from a suspect or victim that can be compared to crime-scene evidence

primary crime scene

the location where the crime took place

recognized, selectively collected, preserved properly

Evidence must be

..• Police officers are usually the first to arrive at a crime scene. A district attorney may be present to determine whether a search warrant is necessary for the crime-scene investigators. • Crime-scene investigators document the crime scene in detail and collect physical evidence. Crime-scene investigators include recorders to record the data, sketch artists to sketch the scene, photographers to take photos of the crime scene, and evidence collectors. • Medical examiners (also called coroners) may be necessary to determine the cause of a death when a homicide has occurred.

describe the role of each of the following people at a crime scene a)police officer b)crime scene investigator c) medical examiner

hair, fiber, glass, soil

identify four examples of trace evidence

individual evidence

a kind of evidence that identifies a particular person or thing. Eyewitness accounts or a police dashboard video camera.

That person takes it to the lab and signs it over to a technician, who opens the package for examination at a location other than the sealed edge. On completion of the examination, the technician repackages the evidence with its original packaging, reseals the evidence in a new packaging, and signs the chain-of-custody log attached to the packaging.

describe how the evidence bag is opened and resealed as diff technicians examine the evidence

• Detectives look for leads by interviewing witnesses and talking to the crime-scene investigators about the evidence. • Specialists such as entomologists (insect biologists), forensic scientists, and forensic psychologists may be consulted if the evidence requires their expertise.

describe the role d) detective e) other specialists

Transfer, loss, or contamination of evidence can occur if the area is left unsecured

describe using specific examples how failing to secure the crime scene leads to contamination of the evidence

the intensity, duration, and nature of the materials in contact determine the extent of the transfer. More transfer would be noted if two individuals engaged in a fistfight than if a person simply brushed past another person.

discuss how the intensity, duration and nature of the materials in contact can affect the extent of the transfer

..The safety of all individuals in the area is the first priority. Preservation of evidence is the second priority

discuss the first and second priority of the first responding officer

.labs and reconstructing crime scene

discuss the role of technology in documenting a crime scene

firsthand observations such as eyewitness accounts or police dashboard video cameras

discuss what is meant by direct evidence

.primary crime scene-where the crime took place, the location secondary crime scene-other than the primary crime, a location scene, but that is in some way related to the crime, where evidence is found

distinguish between a primary and a secondary crime scene

Physical evidence includes impressions such as fingerprints, footprints, shoe prints, tire impressions, and tool marks. Physical evidence also includes fibers, weapons, bullets, and shell casings. Biological evidence includes body fluids, hair, plant parts, and natural fibers. Most physical evidence, with the exception of fingerprints, reduces the number of suspects to a specific, smaller group of individuals. Biological evidence may make the group of suspects very small, or reduce it to a likely individual, which is more persuasive in court.

distinguish between physical and biological circumstantial evidence

Crime scene investigators

document crime scene and collect evidence. assess the extent of the crime scene. includes lead investigator, photographer, sketch artist, evidence collector, evidence custodian. must disturb things as little as possible. particular attention should be paid to the floor.

.Photos of the overall area and close-up photos with and without a measuring ruler should be taken. Triangulation of stationary objects should be included in the photos as reference points. A view of the crime scene should be taken from several different angles and distances. Several close-up photos of any evidence and bodies should be taken.

elaborate on the idea of "seeing the scene" include in your answer what type of photos needs to be taken of the crime scene and the importance of a ruler being placed in the photo

Circumstantial Evidence

indirect evidence that can be used to imply a fact but does not directly prove it (physical and biological)

hair, fingerprints, soil, blood, paint chips, glass

list at least 4 examples of materials that could be transferred form crime scene to a suspect

.hair, fingerprints, soil, blood, paint chips, glass

list at least 4 items of materials that could be transferred form a suspect to a crime scene

.• When did the crime occur? • Who called in the crime? • Who is the victim? • Can the perpetrator be identified? • What did you see happen? • Where were you when you observed the crime scene?

list several question that an investigator might ask a witness to a crime

recognize, document, and collect evidence at the scene of a crime

list three goals of a crime scene investigator

class evidence

material that connects an individual or thing to a certain group

Medical examiners

may be necessary to determine cause of death

Photography

overall photos of the scene are taken before evidence is recovered, from several different angles, object must not be moved until they have been photographed, close ups should be taken, a ruler or other measuring scale should be inserted, photo log, digital camera photos cannot be used as evidence in court

First responders

police officers who discover and secure the crime scene. First priority is the safety of all individuals. Assist or preserve the life of the victim.

Chain of Custody

record of all of the individuals who maintained unbroken control over the items of evidence. single most important piece of paper generated at the crime scene. established that the evidence collected is the evidence being presented in court

trace evidence

small but measurable amounts of physical or biological materials found at a crime scene

Forensic Entomology

study of insects and their relation to a criminal investigation, commonly used to estimate the time of death. Blowfly first on crime scene.

.A forensic lab processes all of the evidence the crime-scene investigation collected to determine the facts of the case

describe how evidence from a crime scene is analyzed

Preservation

properly packaged, sealed, and labeled. kept in separate containers. liquids, charred debris, stored in airtight unbreakable containers. biological evidence in a paper bindle or druggist fold.

when a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur.

summarize locards exchange principle

secondary crime scene

a location other than the primary crime scene, but that is in some way related to the crime, where evidence is found

Forensic Pathology

examination of body through autopsy to determine cause of death

crime-scene reconstruction

a hypothesis of the sequence of events from before the crime was committed through its commission

Physical Evidence

any and all objects that can establish that a crime has been committed or can provide a link between a crime and its victim or a crime and its perpetrator

.All evidence needs to be properly packaged, sealed, and labeled. Case number • Item inventory number 26 Crime-Scene Investigation and Evidence Collection 11/30/07 11:33:24 AM • Description of the evidence • Name of suspect • Name of victim • Date and time of recovery • Signature of person recovering the evidence • Signature of any witnesses present during collection

demonstrate proper technique in collecting and packaging trace evidence

How to be a good observer

examine our environment systematically, consciously decide to observe everything, gathering information, write down and photograph

Crime Scene search patterns

spiral (conducted by a single searcher), grid (search strip along one axis, then search the same area on a perpendicular axis), strip or line (indoor or large or open areas, personnel line up shoulder to shoulder arms length), quadrant or zone (area is divided into zones, each person is assigned a zone, group of investigators),

secure the scene, separate the witnesses, scan the scene, seeing the scene, sketching the scene, searching for evidence, securing and collecting evidence, chain of custody

summarize the main duties for each person involved in the seven steps of crime scene investigation 1 2 3 4 5 6 7

.. All objects should be measured from two immovable landmarks. On the sketch, north should be labeled and a scale of distance should be provided. Any other objects in the vicinity of the crime scene should be included in the sketch. This includes doors, windows, and furniture.

explain how a rough sketch of the crime scene is drawn. include in your answer a)how to use at least 2 immovable landmarks when measuring any objects b)how direction should be indicated on the sketch c)the role of a scale of distanced)what other objects should be included in the rough sketch e)what other info should be written on the sketch

.This separation is done to avoid witnesses working together to create a story (collusion).

explain the importance of separating the witnesses at a crime scene

.. Liquids and arson remains are stored in airtight, unbreakable containers. Moist biological evidence is stored in breathable containers so the evidence can dry out, reducing the chance of mold contamination. After the evidence is allowed to air dry, it is packaged in a paper bindle. The bindle (or druggist's fold) can then be placed in a plastic or paper container.

compare and contrast the methods of collecting and packaging 1. liquids and arson remains 2. moist biological evidence 3. dry evidence

.Crime-scene reconstruction involves forming a hypothesis of the sequence of events from before the crime was committed through its commission. The evidence is examined and compared with the witnesses' statements to determine the reliability of their accounts.The investigator looks at the evidence and attempts to determine how it fits into the overall crime scenario. The evidence does not lie, but it could be staged.

describe how a detective will try to reconstruct a crime scene using the documented evidence and any eyewitness accounts of the crime

.1. Choose the appropriate-size sheet of clean paper for the bindle. 2. Crease the paper as shown in the figure. 3. Place evidence in the X location. 4. Fold left and right sides in. 5. Fold in top and bottom. 6. Insert the top flap into the bottom flap then tape closed.

describe how to form and package a paper bindle

.• Case number • Item inventory number • Description of the evidence • Name of suspect • Name of victim • Date and time of recovery • Signature of person recovering the evidence • Signature of any witnesses present during collection

list the items that must appear on an evidence log

Collected and sent to forensic laboratory

victim's clothing, fingernail scrapings, head and pubic hairs, blood, vaginal/anal/and oral swabs (sex-related crimes), recovered bullets from the body, hand swabs from shooting victims.