introduction to forensic science crime scene investigation

Introduction to Forensic Science

Crime Scene Investigation

Participation Question

• Can you give an example of a type of physical evidence that would be unstable or hard to collect at a crime scene? Can you suggest a way to document that evidence for trial?

Goal of Crime Investigation

• Find the guilty party.• Exonerate the innocent.• If the investigator doesn’t preserve the

evidence or document that preservation correctly, the evidence isn’t useful in court.

• Crime Laboratory can’t make the evidence make sense if it isn’t collected correctly.

Two Evidence Types

• Testimonial evidence is given in the form of a statement under oath in response to questioning.

• Physical evidence is anything used, left, removed, altered or contaminated during the commission of the crime, by either the victim(s) or suspect(s).

Physical Evidence

• Cannot lie, forget, be mistaken when properly identified, collected and preserved.

• Is demonstrable.• Is not dependent on the presence of

witnesses.• Is, in some instances, the only way to establish

the elements of the crime.

Two Types of Physical Evidence

• Individual Characteristics. – A piece of evidence that is unique and can be

identified to the exclusion of all others.– Fingerprints– DNA

• Class Characteristics– Features shared by all members of a group or

class– Footprints

ARISN

• Approach.• Render medical aid.• Identify additional victims or witnesses.• Secure the scene and physical evidence.• Notifications made appropriately.

Approach

• Drive carefully- Sirens and high speed can be risky.

• Scan for suspicious things or persons.• Be alert to evidence, witnesses and victims.• Call for more help and don’t dismiss the help

until the situation is clear.

Rendering Medical Aid

• The most important issue is to save a human life or prevent additional injury.

• If the crime scene becomes contaminated while rendering aid, that is a price that must be paid.

• There aren’t hard and fast rules that can be applied- discretion must be used.

Identifying Witnesses/Victims

• May need medical attention.• Witnesses identify suspects and locations of

additional evidence.• Separate the witnesses so they don’t cross-

contaminate stories.• Be observant if witnesses give identical

stories- they may have collaborated before police arrived.

Secure the Scene

• Establish a perimeter.– Yellow tape.– Barriers.– Close the door for indoor crimes.– Police officers.

• Secure scene and evidence.– Check for exit strategy of the criminal and follow

to check for additional evidence.

Secure the Scene

• Crime Scene Log is used to document the investigation:– Who entered the scene– Who left the scene– Time In and Out– Reason for entry to the scene

• Keep out unauthorized police or fire personnel.

Make Notifications

• First Responders notify superiors.• Call in Crime Scene Specialists:

– Photo Specialists– Medical Examiners– Crime Scene Units

Types of Scenes

• Major Scenes– Homicides– Officer involved shootings– DUI casualties– Felonious assaults in which death could occur.– Cases with potential for a major investigation

• Non-major or discretionary

Major Indoor Scenes: Observations and Notes

• Time• Entrances and Exits

– Doors• Open• Closed• Locked• Type of lock (e.g. deadbolt)• Forced

Major Indoor Scenes Cont..

– Windows• Open• Closed• Locked• Unlocked

– Lights (on/off)– Odors

• Cigarettes, cigars, perfume, alcohol, gas, gun powder, unusual odors.


• Names of Persons at the scene, including emergency personnel.

• Condition of the scene:– In disarray/good order– Furniture tossed about– Stains– Position of weapons


• Avoid the following:– Do not touch inside doors, doors and door frames.– Do not move anything.– Do not smoke, or use the telephone, toilet, sink or

ashtrays.– Beware where you stand and what you touch.

Hold your hand behind your back while surveying the crime scene.

Outdoor Crime Scenes

• Establish and protect a large perimeter, especially at parks, beaches or open areas.

• If tire/footprint or other impression evidence is found, warn others to stay away.

• Try to determine the suspect’s route of approach and escape.

• Identify and protect evidence, then collect it. Some evidence is difficult to collect.

Secondary Crime Scenes

• Evidence may be located some distance from the original crime scene:– Discarded clothing– Discarded weapons– Blood trails

• Protect secondary crime scene evidence as well as primary crime scenes.

Death Cases

• Four methods by which death can occur:– Natural Causes– Accidental Death– Suicide– Homicide

• Medical Examiner makes this decision.

Death Cases

• All death scenes should be treated like a homicide until the medical examiner declares otherwise.

• First responders should not hesitate to ask for assistance if needed. Better to err on the side of caution.

• Key to a successful investigation is documentation.

Death Cases

• Make note of some of the following:– Believability of the witnesses.

• Jittery, nervous, anxious to leave the scene?• Does their version of the incident seem questionable?

– Condition of the scene.– History of the victim and/or suspect if known.– Preservation of notes or writing for later analysis.– Preserve medications and containers.

Documenting the Crime Scene

• Investigators have only a limited amount of time to work a crime site in its untouched state.

• Photographs, notes and diagrams document the condition of the crime site and to delineate the location of physical evidence.

• Photographs, notes and diagrams prove useful during the subsequent investigation AND are also required for presentation at a trial often months or years later.

PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ 07458

CRIMINALISTICS An Introduction to Forensic Science, 9/EBy Richard Saferstein

Documenting the Crime Scene

• A lead investigator will start the process of evaluating the area before collecting evidence. – First, the boundaries of the scene must be determined.– This is 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.



Crime Scene Search

• The crime scene coordinator may choose from a variety of crime scene search patterns based upon the type and size of the crime scene.

• Key is to be orderly and thorough- don’t walk over too much but don’t miss anything.

(a) Spiral

(b) Strip/Line

(c) Grid

(d) Zone/Quadrant

(e) Pie/Wheel

The Search

• The search for physical evidence at a crime scene must be thorough and systematic.

• The search pattern selected will normally depend on the size and locale of the scene and the number of evidence collectors.

• Physical evidence can be anything from massive objects to microscopic traces.



Collecting Physical Evidence

• Although much physical evidence is clearly visible, some may only be detected at the crime laboratory.– E.g. Semen on sheets after a sexual assault.

• It is important to notice and collect possible carriers of trace evidence, such as clothing, vacuum sweepings, and fingernail scrapings, in addition to more obvious physical evidence.

• Investigators need to keep from contaminating the evidence- e.g. their DNA or fibers.

The Victim Can Provide Evidence

• The search for physical evidence must continue to the autopsy room of a deceased victim.

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

• Tissues and organs will be retained for pathological and toxicological examination.

• Also they will provide any physical evidence from the body of the victim.



Beyond The Crime Scene

The following are often 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 body7. Hand swabs from shooting victims (for gunshot residue

analysis)PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ 07458


Collecting and Packaging Evidence

• 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 other kinds of trace evidence.

• Manila envelopes, screw-cap glass vials, or cardboard pillboxes are also good containers

• Ordinary mailing envelopes should not be used because powders will leak out of their corners.

Packaging to Preserve Evidence

• Each item or similar items collected at different locations must be placed in separate containers.

• Packaging evidence separately prevents damage through contact and prevents cross-contamination.

• The well-prepared evidence collector will have a large assortment of packaging materials and tools ready to encounter any type of situation.



Packaging

• Trace evidence can also be packaged in a carefully folded paper, using a “druggist fold.”

• Two frequent finds at crime scenes warrant special attention.– 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.



Obtaining Reference Samples• Standard/Reference Sample—Physical evidence whose origin

is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence.

• The examination of evidence, whether it is soil, blood, glass, hair, fibers, and so on, often requires comparison with a known standard/reference sample.

• Although most investigators have little difficulty recognizing and collecting relevant crime-scene evidence, few seem aware of the necessity and importance of providing the crime lab with a thorough sampling of standard/reference materials.



Evidence Recovery Log

• A chronological record of who found what evidence, where, witnessed by whom, and notations about other ways the evidence may have been documented, e.g., photography

Evidence Recovery Log

Records are critical for prosecution of the crime as well as records of unbroken chain of evidence.

Chain of Custody

• Chain of Custody—A list of all persons who came into possession of an item of evidence.

• The chain of custody, must be established whenever evidence is presented in court.

• Adherence to standard procedures in recording its location, marking it for identification, and properly completing evidence submission forms for laboratory analysis is critical.

• Every person who handled the evidence and where it was at all times must be documented.



Case Studies

• O.J. Simpson – Evidence not handled well, leading it suggestions

it was compromised by dishonest criminalists and police.

• JonBenet Ramsey– Crime scene wasn’t secured and family friends

and father found body, contaminating the scene.

Notes

• Notes must include a detailed written description of the scene with the location of items of physical evidence recovered.

• Notes must identify:– the time an item of physical evidence was discovered– by whom it was discovered– how and by whom it was packaged and marked– the disposition of the item after it was collected

• This written record may be the only source of information for refreshing one’s memory!



Visually Documenting the Crime Scene Is Critical

• Video taping• Photographing• Sketching

Photography• The most important prerequisite for photographing a

crime scene is for it to be in an unaltered condition. • Unless there are injured parties involved, objects

must not be moved until they have been photographed from all necessary angles.

• As items of physical evidence are discovered, they are photographed to show their position, size and location relative to the entire scene.



Photography

• After overviews are taken, close-ups should be taken to record the details of the object itself.

• A ruler or other measuring scale may be placed near the object and included in the photograph.

• Once photographs are taken, the crime-scene investigator will sketch the scene.



Photography

• Photograph the crime scene as soon as possible.

• Prepare a photographic log that records all photographs and a description and location of evidence.

• Establish a progression of overall, medium, and close-up views of the crime scene.

• Photograph from eye level to represent the normal view.

Photography

• Photograph the most fragile areas of the crime scene first.

• Photograph all stages of the crime scene investigation, including discoveries.

• Photograph the condition of evidence before recovery.

• Photograph the evidence in detail and include a scale, the photographer's initials, and the date.

Photography

• When a scale is used, first take a photograph without the scale.

• Photograph the interior crime scene in an overall and overlapping series using a wide-angle lens.

• Photograph the exterior crime scene, establishing the location of the scene by a series of overall photographs including a landmark. Photographs should have 360 degrees of coverage. Consider using aerial photography.

• Photograph entrances and exits.

Photography

• Photograph important evidence twice.• A medium-distance photograph that shows

the evidence and its position to other evidence.

• A close-up photograph that includes a scale and fills the frame.

• Acquire prior photographs, blueprints, or maps of the scene.

Sketches

• Rough Sketch—A representation of all essential information, evidence and measurements at a crime scene drawn at the crime scene.

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



Sketches can illustrate where evidence was collected

Vandalia Science Education ©2007 Vandalia Research, Inc. Huntington, WV 25701

Crime Scene Safety• Potential health hazards exist at crime scenes.• Chemicals (e.g. methamphetamine production) are

hazardous.• AIDS and hepatitis B and C are two possible blood born

diseases that can be transmitted. • Law enforcement officers have a very small chance of

contracting AIDS or hepatitis at the crime scene.• The International Association for Identification Safety

Committee has proposed guidelines to protect investigators at crime scenes.

• Universal Precautions- assume all body fluids are contagious.

Search and Seizure Legality

• The US Supreme Court precedents for 4th Amendment justify search and seizure of evidence without a court-approved warrant under these conditions: 1) Emergency circumstances2) The need to prevent the immediate loss or destruction of

evidence3) A search of a person and property within the immediate

control of the person, provided it is made incident to a lawful arrest

4) A search made by consent of the parties involved

Landmark Cases• Mincy vs. Arizona (1978):

– Police officers may make warrantless entries and searches if they believe someone needs aid

– However, to return later to gather additional evidence, the police must have a warrant

• Michigan vs. Tyler:– Fire investigators may search and gather evidence for a

reasonable time following a fire– However by the next day, to gather additional evidence

investigators must obtain a warrant



http://www.law.cornell.edu/supct/html/historics/USSC_CR_0437_0385_ZS.html

“Crime Scene Exception" to the 4th Amendment?

• James Michael Flippo v. West Virginia (1999)• One night in 1996, petitioner and his wife were vacationing at a cabin in a state park. After

petitioner called 911 to report that they had been attacked, the police arrived to find petitioner waiting outside the cabin, with injuries to his head and legs. After questioning him, an officer entered the building and found the body of petitioner’s wife, with fatal head wounds. The officers closed off the area, took petitioner to the hospital, and searched the exterior and environs of the cabin for footprints or signs of forced entry. When a police photographer arrived at about 5:30 a.m., the officers reentered the building and proceeded to “process the crime scene.” Brief in Opposition 5. For over 16 hours, they took photographs, collected evidence, and searched through the contents of the cabin. According to the trial court, “[a]t the crime scene, the investigating officers found on a table in Cabin 13, among other things, a briefcase, which they, in the ordinary course of investigating a homicide, opened, wherein they found and seized various photographs and negatives.”

• On appeal, the United States Supreme Court disagreed, holding that "searches conducted outside of the judicial process, without prior approval by a judge...are per se unreasonable under the Fourth Amendment". 437 U.S. at 390. Thus, absent an emergency threatening life or limb, a warrantless search of a crime scene is unconstitutional. In sum, there is no "crime scene exception" to the search warrant requirement.

• The result in Flippo is consistent with Mincey. Law enforcement officers remained in the cabin for sixteen hours to conduct the warrantless search of the homicide scene. This was obviously illegal, and the State court ruling admitting the evidence was reversed.

http://supct.law.cornell.edu/supct/html/98-8770.ZPC.html

introduction to forensic science crime scene investigation

Documents

scene crime scene log

secure scene

piece of evidence

discretionary slide

crime scene specialists

scene time

type of physical evidence

evidence isnt useful