Crime Scene Investigation Forensic Science. Copyright © Texas Education Agency 2011. All rights reserved. Images and other multimedia content used with.

Crime Scene Investigation

Forensic Science

Copyright © Texas Education Agency 2011. All rights reserved.Images and other multimedia content used with permission.

Physical Evidence

•As automobiles run on gasoline, crime laboratories “run” on physical evidence.

•Physical evidence encompasses 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.


The Beginning

•Forensic science begins at the crime scene.

•If the investigator cannot recognize physical evidence or cannot properly preserve it for laboratory examination, no amount of sophisticated laboratory instrumentation or technical expertise can salvage the situation.

4Copyright © Texas Education Agency 2011. All rights reserved.Images and other multimedia content used with permission.

Processing a Crime Scene

1. Isolate and secure the scene

2. Document the scene

3. Search for evidence

4. Collect and package the evidence while maintaining the chain of custody

5. Submit the evidence for analysis


First Officer on the Scene

A – Assess the crime scene and assist the injured

D – Detain the witness(es)

A – Arrest the perpetrator

P – Protect the crime scene

T – Take notes


1. Isolate and Secure the Crime Scene

a. Look for signs of lifeb. Cordon off the scene (only allow

authorized personnel in)c. Bodies should be certified as

“dead” by a medical examiner (ME) before being moved


1. Isolate and Secure the Crime Scene :Survey the Crime Scene

A walkthrough is performed by the crime scene investigator, the first officer, and sometimes the lead detectivea. Determine the boundaries of the

crime sceneb. Record initial observations of

who, what, where, when, and howc. Make a plan of action


2. Document the Crime Scene•Record the crime scene and potential evidence withA. NotesB. PhotographyC. SketchesD. Videography


A. Notes

• Record the following while at the crime scene (details are the key):

•Date•Time•Description of the location, weather, and environmental conditions

•Description of the crime •Location of the evidence relative to other key points

•Names of all people involved•Any other relevant information


B. Photography

•Nothing should be moved until photographed

•Take photos of the scene and the surroundings

•Photograph entrances and exits•Take wide and close-up photos•Use various angles for each piece of evidence

•Use a ruler to show size


C. Videography

•Narrate the video•Be objective•Record from different perspectives


D. Sketches• Draw a rough sketch at the scene (reconstruct it better later)

• Include•Date, time, and location•Scale•Recovered items• Important features•Accurate distance measurements of objects (from two fixed points)

•A legend for description of items•A compass designating north•Names of investigators, victims, and suspects


Example: Rough Sketch Include 2 lines to show distance from evidence to a reference point, such as the wall


D. Sketches

•Finished Sketch —A precise rendering of the crime scene, usually drawn to scale. This type is not normally completed at the crime scene.

•Unlike the rough sketch, the finished sketch is drawn with care and concern for aesthetic appearance.


Finished Sketch


3. Search for Evidence: The Preliminary Exam

•A lead investigator will start the process of evaluating the area. •First, the boundaries of the scene must be determined

•Followed by the establishment of the perpetrator’s path of entry and exit.

•The investigator then proceeds with an initial walk-through of the scene to gain an overview of the situation and develop a strategy for the systematic examination and documentation of the entire crime scene.


3. Search for Evidence:Search Patterns

•Depend on the size and the location of the crime scene and the number of investigators available

•Must be thorough and systematic. •Stick to one pattern and one supervisor•Better to collect everything and not need it than fail to collect something and need it later


Search Patterns (continued)

•Spiral – may move inward or outward; best used where there are no physical barriers

•Grid – basically a double-line search; effective, but time-consuming

•Line (Strip) – best in large, outdoor scenes

•Zone (Quadrant) – most effective in houses or buildings; teams are assigned small zones for searching


Search Patterns


3. Search for Evidence:Searching the Crime

Scene•Often, many items of evidence are clearly visible but others may be detected only through examination at the crime laboratory.

•For this reason, it is important to collect possible carriers of trace evidence, such as clothing, vacuum sweepings, and fingernail scrapings, in addition to more obvious items.


Searching the Crime Scene

• When searching a crime scene, wear the following, if available, to minimize contamination

•Disposable gloves•Masks•Coveralls with a hood•Slippers


3. Search for Evidence:The Body

•The search for physical evidence must extend beyond the crime scene to the autopsy room of a deceased victim.

•Here, the medical examiner or coroner will carefully examine the victim to establish a cause and manner of death.


3. Search for Evidence:Biological Samples

•As a matter of routine, tissues and organs will be retained for pathological and toxicological examination.

•At the same time, arrangements must be made between the examiner and investigator to secure a variety of items that may be obtainable from the body for laboratory examination.



The following are to be collected and sent to the forensic laboratory:

1. Victim’s clothing2. Fingernail scrapings3. Head and pubic hairs4. Blood (for DNA typing

purposes)



5. Vaginal, anal, and oral swabs (in sex-related crimes)

6. Recovered bullets from the body

7. Hand swabs from shooting victims (for gunshot

residue analysis)


4. Collect & Package Evidence

•Physical evidence must be packaged and collected before time and weather can alter it

•Physical evidence – any object that can establish that a crime has been committed or links a crime and the victim or suspect

•The Golden Hour – the window of opportunity to collect time-sensitive information or evidence


4. Collect & Package Evidence (continued)

• Each item must be placed in a separate container, and sealed and labeled

• The most fragile evidence is collected and packaged first

• Different types of evidence require specific or special collection and packaging techniques

• The body is the property of the coroner or medical examiner; collection of evidence on the body is done by that department



•Forceps and similar tools may have to be used to pick up small items.

•Unbreakable plastic pill bottles with pressure lids are excellent containers for hairs, glass, fibers, and various other kinds of small or trace evidence.

•Containers such as vials, envelopes, plastic bags, paper bags, canisters, and cardboard boxes are good packaging devices



• If bloodstained materials are stored in airtight containers, the accumulation of moisture may encourage the growth of mold, which can destroy the evidential value of blood.

• In these instances, wrapping paper, manila envelopes, or paper bags are recommended packaging materials.



•Most items should be placed in a primary container and then in a secondary container

•Trace evidence may be placed on a piece of paper which is then folded in a “druggist fold” and placed in a secondary container



•Containers should be sealed with tamper proof tape, and dated and initialed

•Each package should contain • Description of contents• Date, time, and location• Agency and collector’s name• Case number• Victim’s name(s)

•Never package two items from two different sources or locations


4. Chain of Custody

•Chain of Custody —A list of all persons who came into possession of an item of evidence, including dates, times and signatures.

•Continuity of possession, or the chain of custody, must be established whenever evidence is presented in court as an exhibit.


Crime Scene Processing Video

• 10 minutes• https://www.youtube.com/watch?v=ur1GxXZGnNI

https://www.youtube.com/watch?v=ur1GxXZGnNI

https://www.youtube.com/watch?v=ur1GxXZGnNI


5. Analysis:Crime Scene

Reconstruction•Crime-scene reconstruction relies on the combined efforts of medical examiners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime.

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5. Analysis:Crime Scene

Reconstruction• Investigators put together information gathered from physical evidence, witness statements, crime scene sketches, autopsy reports, photographs, etc. to try to reconstruct how the crime occurred.

•A successful crime scene reconstruction should demonstrate the relationship among the victim, the suspect, and the crime scene.

• If successful, reconstruction can play a vital role in aiding a jury to arrive at an appropriate verdict.

37


Crime Scene Reconstruction Video

• 2:23 min• https://www.youtube.com/watch?v=Fn2cCVgZ-wk

• 2:15 min• https://www.youtube.com/watch?v=1CSrtgYxcr4

https://www.youtube.com/watch?v=Fn2cCVgZ-wk

https://www.youtube.com/watch?v=Fn2cCVgZ-wk

https://www.youtube.com/watch?v=1CSrtgYxcr4

https://www.youtube.com/watch?v=1CSrtgYxcr4


Video Clip: Crime Scene Cleaners

• Suicide 4:41 min• https://www.youtube.com/watch?v=Ys09c9lANjI

• Gorey Crime Scene 3:31 min• https://www.youtube.com/watch?v=PZ1scfEbrKE

https://www.youtube.com/watch?v=Ys09c9lANjI

https://www.youtube.com/watch?v=Ys09c9lANjI

https://www.youtube.com/watch?v=PZ1scfEbrKE

https://www.youtube.com/watch?v=PZ1scfEbrKE


5. Analysis:Forensic Pathology

•Forensic Pathology involves the investigation of unnatural, unexplained, or violent deaths.•Forensic pathologists in their role as medical examiners or coroners are charged with determining cause of death.


5. Analysis:Forensic Pathology: Rigor Mortis

•After a human body expires there are several stages of death:•Rigor mortis results in the shortening of muscle tissue and the stiffening of body parts in the position at death (occurs within the first 24 hrs. and disappears within 36 hrs.).


5. Analysis:Forensic Pathology: Rigor Mortis

43

Forensic Pathology: Rigor Mortis

Temperature Stiffness Time Since of body of body Death

• Warm

• Warm

• Cold

• Cold

• Not stiff

• Stiff

• Stiff

• Not stiff

•Not dead more than 3 hrs

•Dead between 3 and 8 hrs

•Dead 8 to 36 hours

•Dead more than 36 hours


Forensic Pathology: Livor Mortis•Livor mortis results in the settling of blood in areas of the body closest to the ground; Causes the skin to change colors•Lividity indicates the position of the body after death.

•When lividity becomes fixed, then the distribution of the lividity pattern will not change even if the body’s position is altered.

•Begins immediately on death and continues up to 12 hrs.

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Lighter spots appear where the body was resting against the ground (less blood able to collect here).

Dark patches indicate areas where blood was able to collect (close to the ground)


Forensic Pathology: Algor Mortis

•Algor mortis results in the loss of heat by a body

•As a general rule, beginning about an hour after death, the body loses heat by 1 to 1 1/2 degrees Fahrenheit per hour until the body reaches the environmental temperature.

Kendall/Hunt Publishing Company 47Copyright © Texas Education Agency 2011. All rights reserved.Images and other multimedia content used with permission.

Factors that Affect Algor Mortis1. Temperature of the surrounding

environment2. Type of clothing on the body3. Wetness of the clothing4. Air movement5. Layers of clothing6. Size of the individual


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Forensic Pathology: Estimating Time of Death

ConditionPeriphery blood drying

Blue-green discoloration of skinRight and left area of abdomen

Entire abdomen

BloatingSkin slippage

Absence of smell from bones

Appearance30 min to 2 hrs

24 hrs

36 hrs36 to 48 hrs4 to 7 daysMore than 1 year


49

Forensic Pathology: Estimating Time of Death

Condition• Cornea drying (eyes open)

• Cornea drying (eyes closed)

• Corneal cloudiness (eyes open)

• Corneal cloudiness (eyes closed)

• Eyeball collapse

Appearanceminutes2 hour

less than 2 hours12 to 24 hours

more than 24 hrs


Video Clip:Post-Mortem Analysis

• 6:29 min• https://www.youtube.com/watch?v=UC61_KAPwpY

https://www.youtube.com/watch?v=UC61_KAPwpY

https://www.youtube.com/watch?v=UC61_KAPwpY


5. Analysis:Forensic Anthropology

•FORENSIC ANTHROPOLOGISTS analyze skeletal remains to determine the identity of a victim as well as his/her life history, cause of death, or other clues about a crime.

Courtesy of C. Fanning

Courtesy of C. Fanning


Video Clip:BONES, season 1 episode 1

• 37:18 – 35:40• Estimating age and gender of a skeleton

• (Netflix)


Forensic Anthropology• DNA samples can be collected from bone, teeth, and hair to provide clues to a person’s identity.

• Scientists may also be able to gain clues as to a person’s past, recent injuries, or the cause of death based on bone fractures and other signs of trauma. Damage from a

hammer

Gunshot Wounds

Healed Fractures


Forensic Anthropology

Main Characteristics:•Sex - Determined by examining the skull, pelvis, humerus, and femur

•Age and stature (height/build) – Determined by analyzing the development of the teeth, bone growth, cranial suture lines, and the length of specific bones, such as the femur.

•Race – Determined by analyzing the skull for characteristics that are common among people of different races.


Forensic Anthropology: Age Determination

•Most accurate estimations from:•Teeth•Epiphyses or growth plates (ends of long bones)

•Pubic symphysis•Cranial sutures: the three major cranial sutures appear as distinct lines in youth and gradually close from the inside out.

• Investigators always use an age range because of the variation inn individual people and how they age.


Forensic Anthropology: Age Determination

• Epiphyseal Growth Plates:

Kendall/Hunt Publishing Company 57

Forensic Anthropology : Age Determination Using Cranial Sutures

All sutures completely open:Male—less than 32Female—less than 35

Sagittal suture and Coronal suture partially closed:

31 – 45 years

Lambdoid suture begins to close

• Over 41

Complete closure of all three major sutures:

Over 45 years

Sagittal suture

Lambdoid Coronal


Forensic Anthropology: Age Determination Using Basilar Suture

Basilar SutureTechnically known as the

synchondrosis spheno-occipitalis,

Closes in females as young as 14 and in males as young as 16.

If the suture is open, the individual is generally considered 18 or younger.


Forensic Anthropology: Gender Differences in Bones

The pelvis of the female is wider. Males have a narrow subpubic angle (A) and a narrow pubic body (B).

Male Female

Sub Pubic Angle


Forensic Anthropology: Gender Differences

The ribcage and shoulders of males are generally wider and larger than that of females.


Forensic Anthropology: Gender Differences

In males the index finger is sometimes shorter than the third finger. In females, the first finger is sometimes longer than the third finger. This is not often used as an indicator of gender as there are many exceptions.

Is this a male or female hand according to the above rule?


Video Clip:Human Identification

• 11 min• https://www.youtube.com/watch?v=o2UgIMQ_lII

https://www.youtube.com/watch?v=o2UgIMQ_lII

https://www.youtube.com/watch?v=o2UgIMQ_lII


Forensic Anthropology: Determining Race

Race is difficult to determine from most skeletal remains, especially since pure races are becoming uncommon.

An experienced forensic anthropologist can generally place skulls into one of three groups:Caucasian—European, Middle Eastern, and Indian

descentNegroid—African, Aborigine, and Melanesian descent Mongoloid—Asian, Native American and Polynesian

descent


Forensic Anthropology: Race CharacteristicsCaucasoids—have a long, narrow nasal aperture, a triangular palate, oval orbits, narrow zygomatic arches and narrow mandibles.

Negroids—have a wide nasal aperture, a rectangular palate, square orbits, and more pronounced zygomatic arches. The long bones are longer, have less curvature and greater density.

Mongoloids—have a more rounded nasal aperture, a parabolic palate, rounded orbits, wide zygomatic arches and more pointed mandibles.


What differences do you notice between these three skulls? Can you determine race?


Forensic Anthropology: Odontology

•The identity of an individual can be determined by comparing a person’s teeth to their dental records.

•Unusual features including the number and types of teeth and fillings, the spacing of the teeth, and/or special dental work (bridges, false teeth, root canals) help to make a positive identification.


Forensic Anthropology: Odontology andIdentification

•Teeth are often used for body identification because:•They are the hardest substances in the body

•They are unique to the individual•X-rays are a good record of teeth


Forensic Anthropology: Facial Restoration

After determining the sex, age, and race of an individual, facial features can be built upon a skull to assist in identification.

Erasers are used to make tissue depths at various points on the skull.

Clay is used to build around these markers and facial features are molded.


Forensic Anthropology: Steps in Facial Reconstruction

With a skull: Establish age, sex and race Plot landmarks for tissue

thickness Plot origin and insertion points for

muscles Plot landmarks for facial features Select a dataset and mount

markers for tissue thickness Mount the eyes

Model muscles on skull Add fatty tissue around

eyes and lacrimal glands Add eyelids Add the nose Add the parotid gland Add the ears Cover all with layers of skin Detail the face


Video Clip: BONES, Season 1 episode 1

• 29:30 – 27:35• Modeling facial features from a skull• Note: this 3D software program is fictional, but the process is real (normally done with modeling clay) (Netflix)


5. Analysis:Forensic Entomology

•Forensic Entomology is the study of insects and their relation to a criminal investigation, commonly used to estimate the time of death.


Video Clip:Forensic Entomology

• 7:27 min• https://www.youtube.com/watch?v=HIVKISCmjTQ

https://www.youtube.com/watch?v=HIVKISCmjTQ

https://www.youtube.com/watch?v=HIVKISCmjTQ


National Databases

•Crime Scene Investigators can submit evidence for analysis to several national databases based on the type of evidence

•Examples include •Automated Fingerprint Identification System (AFIS)

• Integrated Automated Fingerprint Identification System (IAFIS)

•Combined DNA Index System (CODIS)• Integrated Ballistics Identification System (IBIS)

• International Forensic Automotive Paint Data Query (PDQ)

75

Solving a Crime

+ =

What Happened?

Why Did ItHappened?

Who DidIt?

Crime Scene Evidence Collection Witness, Suspect and Motive Development

Post Scene Evidence Processing Cause, manner, time of death

Investigative Stage Psychological

Profiling Means Motive Opportunity

Identificationand Arrest of

Suspect

76

Just A Thought

It’s not what you know that hurts you, its what you think you know and it’s not so . . . . .Mark Twain

How does this apply to forensic science and crime investigations?


Resources

• 0135158494, Saferstein, Richard. Forensic Science: An Introduction. New Jersey: Pearson Prentice Hall, 2008.

• 0757518257, Ball-Deslich, Barbara and John Funkhouser. Forensic Science for High School. 2nd Edition. Kenall/Hunt, 2009.

Crime Scene Investigation Forensic Science. Copyright © Texas Education Agency 2011. All rights reserved. Images and other multimedia content used with.

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