Crime SceneCrime Scene

Physical Evidence- encompasses any Physical Evidence- encompasses any and all objects that can establish and all objects that can establish that a crime has been committed or that a crime has been committed or can provide a link between a crime can provide a link between a crime and its victim or a crime and its and its victim or a crime and its perpetrator; anything that is perpetrator; anything that is tangible, can be seen or measured, tangible, can be seen or measured, with or without magnificationwith or without magnification

So why aren’t all crimes So why aren’t all crimes solved?solved?

If physical evidence is to be used effectively If physical evidence is to be used effectively for aiding the investigator, its presence first for aiding the investigator, its presence first must be recognized at the crime scene.must be recognized at the crime scene.

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

It must be emphasized that the techniques of It must be emphasized that the techniques of crime-scene investigation are not difficult to crime-scene investigation are not difficult to master and certainly lie within the bounds of master and certainly lie within the bounds of comprehension of the average police officer.comprehension of the average police officer.

The First StepsThe First Steps 11-Assess the -Assess the nature of the scenenature of the scene 22-The first officer to arrive at the scene is -The first officer to arrive at the scene is

responsible for responsible for securing the crime scenesecuring the crime scene. . 33-First priority should be given to obtaining -First priority should be given to obtaining

medical assistancemedical assistance for individuals in need of it for individuals in need of it and to and to arresting the perpetrator.arresting the perpetrator.

44-As soon as it is possible, extensive efforts must -As soon as it is possible, extensive efforts must be made to exclude all unauthorized personnel be made to exclude all unauthorized personnel from thefrom the scene.scene. Protect the scene Protect the scene

55--Recording of the crime sceneRecording of the crime scene becomes a becomes a critical piece to the investigation process.critical piece to the investigation process.

Recording MethodsRecording Methods

Photography, sketches, and notes Photography, sketches, and notes are the three methods for crime-are the three methods for crime-scene recording.scene recording.

Ideally all three should be employed; Ideally all three should be employed; however, as is often the case, however, as is often the case, personnel and monetary limitations personnel and monetary limitations may prohibit the utilization of may prohibit the utilization of photography at every crime site. photography at every crime site.

Searching for EvidenceSearching for Evidence

MethodsMethods Spiral searchSpiral search GridGrid Strip or LineStrip or Line Quadrant or Zone SearchQuadrant or Zone Search

Figure 2–7  Several typical examples of crime-scene search patterns. The pattern selected normally depends on the size and locale of the scene and the number of collectors participating in the search.

PhotographyPhotography The most important prerequisite for The most important prerequisite for

photographing a crime scene is for it to be in photographing a crime scene is for it to be in an unaltered condition.an unaltered condition.

Unless there are injured parties involved, Unless there are injured parties involved, objects must not be moved until they have objects must not be moved until they have been photographed from all necessary angles. been photographed from all necessary angles.

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

After these overviews are taken, close-ups After these overviews are taken, close-ups should be taken to record the details of the should be taken to record the details of the object itself. object itself. When the size of an item is of significance, a ruler When the size of an item is of significance, a ruler

or other measuring scale may be inserted near the or other measuring scale may be inserted near the object and included in the photograph as a point of object and included in the photograph as a point of reference. reference.

SketchesSketches Once photographs are taken, the crime-scene Once photographs are taken, the crime-scene

investigator will sketch the scene. investigator will sketch the scene. Rough SketchRough Sketch—A draft representation of all —A draft representation of all

essential information and measurements at a essential information and measurements at a crime scene. crime scene. This sketch is drawn at the This sketch is drawn at the crime scene.crime scene. It shows all recovered items of It shows all recovered items of physical evidence, as well as other important physical evidence, as well as other important features of the crime scene. features of the crime scene.

Finished SketchFinished Sketch—A precise rendering of the —A precise rendering of the crime scene, usually drawn to scale. This type is crime scene, usually drawn to scale. This type is notnot normally completed at the crime scene. normally completed at the crime scene.

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

Figure 2–4  Rough-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com

Figure 2–5  Finished-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com

NotesNotes Note taking must be a Note taking must be a constant activityconstant activity

throughout the processing of the crime scene.throughout the processing of the crime scene. These notes must include a detailed written These notes must include a detailed written

description of the scene with the location of description of the scene with the location of items of physical evidence recovered. items of physical evidence recovered.

They must identify:They must identify: the time an item of physical evidence was the time an item of physical evidence was

discovered.discovered. by whom.by whom. how and by whom it was packaged and marked.how and by whom it was packaged and marked. the disposition of the item after it was the disposition of the item after it was

collected.collected. The note taker has to keep in mind that this The note taker has to keep in mind that this

written record may be the only source of written record may be the only source of information for refreshing one’s memory.information for refreshing one’s memory.

Recording the Crime Recording the Crime SceneScene

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

The opportunity to permanently record the The opportunity to permanently record the scene in its original state must not be lost. scene in its original state must not be lost.

Such records will not only prove useful during Such records will not only prove useful during the subsequent investigation but are also the subsequent investigation but are also required for presentation at a trial in order to required for presentation at a trial in order to document the condition of the crime site and to document the condition of the crime site and to delineate the location of physical evidence.delineate the location of physical evidence.

Every step of the investigation should be Every step of the investigation should be documented thoroughly with an appropriate documented thoroughly with an appropriate method.method.

The Preliminary ExamThe Preliminary Exam A lead investigator will start the process of A lead investigator will start the process of

evaluating the area.evaluating the area. First, the boundaries of the scene must be First, the boundaries of the scene must be

determineddetermined Followed by the establishment of the Followed by the establishment of the

perpetrator’s path of entry and exit.perpetrator’s path of entry and exit. The investigator then proceeds with an The investigator then proceeds with an

initial walk-through of the scene to gain an initial walk-through of the scene to gain an overview of the situation and develop a overview of the situation and develop a strategy for the systematic examination and strategy for the systematic examination and documentation of the entire crime scene.documentation of the entire crime scene.

This is done before processing the crime This is done before processing the crime scene for physical evidence.scene for physical evidence.

Beyond the Crime SceneBeyond the Crime Scene The search for physical evidence must extend The search for physical evidence must extend

beyond the crime scene to the autopsy room beyond the crime scene to the autopsy room of a deceased victim. of a deceased victim.

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

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

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

Beyond The Crime SceneBeyond The Crime Scene The following are to be collected and sent to The following are to be collected and sent to

the forensic laboratory:the forensic laboratory:1.1. Victim’s clothingVictim’s clothing

2. 2. Fingernail scrapingsFingernail scrapings3. Head and pubic hairs3. Head and pubic hairs4. Blood (for DNA typing purposes)4. Blood (for DNA typing purposes)5.5. Vaginal, anal, and oral swabs (in Vaginal, anal, and oral swabs (in

sex-sex- related crimes)related crimes)6.6. Recovered bullets from the bodyRecovered bullets from the body7.7. Hand swabs from shooting victims Hand swabs from shooting victims

(for gunshot residue analysis)(for gunshot residue analysis)

PackagingPackaging Forceps and similar tools may have to be used Forceps and similar tools may have to be used

to pick up small items. to pick up small items. Unbreakable plastic pill bottles with pressure Unbreakable plastic pill bottles with pressure

lids are excellent containers for hairs, glass, lids are excellent containers for hairs, glass, fibers, and various other kinds of small or fibers, and various other kinds of small or trace evidence. trace evidence.

Alternatively, manila envelopes, screw-cap Alternatively, manila envelopes, screw-cap glass vials, or cardboard pillboxes are glass vials, or cardboard pillboxes are adequate containers for most trace evidence adequate containers for most trace evidence encountered at crime sites. encountered at crime sites.

Ordinary mailing envelopes should not be usedOrdinary mailing envelopes should not be used as evidence containers because powders and as evidence containers because powders and fine particles will leak out of their corners. fine particles will leak out of their corners.

PackagingPackaging Small amounts of trace evidence can also be Small amounts of trace evidence can also be

conveniently packaged in a carefully folded conveniently packaged in a carefully folded paper, using what is known as a “druggist fold.”paper, using what is known as a “druggist fold.”

Although pill bottles, vials, pillboxes, or manila Although pill bottles, vials, pillboxes, or manila envelopes are good universal containers for envelopes are good universal containers for most trace evidence, two frequent finds at crime most trace evidence, two frequent finds at crime scenes warrant special attention.scenes warrant special attention.

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

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

Chain of CustodyChain of Custody Chain of CustodyChain of Custody—A list of all persons who came —A list of all persons who came

into possession of an item of evidence.into possession of an item of evidence. Continuity of possession, or the chain of custody, Continuity of possession, or the chain of custody,

must be established whenever evidence is must be established whenever evidence is presented in court as an exhibit. presented in court as an exhibit.

Adherence to standard procedures in recording Adherence to standard procedures in recording the location of evidence, marking it for the location of evidence, marking it for identification, and properly completing evidence identification, and properly completing evidence submission forms for laboratory analysis is submission forms for laboratory analysis is critical to chain of custody.critical to chain of custody.

This means that every person who handled or This means that every person who handled or examined the evidence and where it is at all examined the evidence and where it is at all times must be accounted for.times must be accounted for.

Obtaining Reference Obtaining Reference SamplesSamples

Standard/Reference SampleStandard/Reference Sample—Physical evidence —Physical evidence whose origin is known, such as blood or hair from whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene a suspect, that can be compared to crime-scene evidence.evidence.

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

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

Comparison- subjects a Comparison- subjects a suspects specimen and control suspects specimen and control

specimen to the same tests specimen to the same tests and examinations for the and examinations for the

ultimate purpose of ultimate purpose of determining whether or not determining whether or not they have a common originthey have a common origin

1.1. Individual- evidence associated Individual- evidence associated with a common source with an with a common source with an extremely high degree of extremely high degree of probabilityprobability

2.2. Class- evidence associated only Class- evidence associated only with a group and never with a with a group and never with a single sourcesingle source

Assurance of Quality Assurance of Quality Control in the LabControl in the Lab

1.1. Duplicate testingDuplicate testing

2.2. Peer review- two scientists Peer review- two scientists independently examine and interpret independently examine and interpret the same test resultsthe same test results

3.3. Supervisor review- senior scientists Supervisor review- senior scientists studies the entire process for studies the entire process for accuracy and completenessaccuracy and completeness

4.4. Follow written procedures of the labFollow written procedures of the lab