Analyzing the Analyzing the Crime SceneCrime Scene

Chapter 2Chapter 2

Forensic ScienceForensic Science

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Approaching a Crime SceneApproaching a Crime Scene

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Approaching a Crime SceneApproaching a Crime Scene

Personal Safety and the well Personal Safety and the well being of victims is paramount. being of victims is paramount.

Secure / Preserve and Isolate Secure / Preserve and Isolate the crime scene. the crime scene. Video

Record the crime scene in Record the crime scene in photos, sketches and notes.photos, sketches and notes.

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Recording the Crime Recording the Crime SceneScene

Photographs /Photographs /videos

Software.. SketchesSketches Notes

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Rough Sketch of the Crime SceneRough Sketch of the Crime Scene

The initial The initial documentation documentation of the crime of the crime scene. scene.

Often a hand Often a hand drawn drawn representation representation of the scene by of the scene by investigators.investigators.

Rough Sketch to FinalRough Sketch to Finalbsapp.com

A computer A computer drawn CAD drawn CAD version of the version of the combination of combination of the rough the rough sketch and sketch and notes from the notes from the investigators.investigators.

NotesNotesMatch to sketchMatch to sketchUse a numbered keyUse a numbered keyQuick, short, bulletedQuick, short, bulletedWhat can you not see from What can you not see from the photo?the photo?

Critical Observations of the Critical Observations of the scene. Use all senses.scene. Use all senses.

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PhotographyPhotography

SceneSceneMultiple Multiple viewsviews

EntrancesEntrancesExitsExitsWindowsWindows

EvidenceEvidenceClose upsClose upsPerspectivPerspectivesesMultiple Multiple anglesangles

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Collecting EvidenceCollecting Evidence Victim's clothingVictim's clothingFingernail scrapingsFingernail scrapingsHead and pubic hairsHead and pubic hairsBlood (for typing Blood (for typing purposes)purposes)

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Vaginal, anal, and oral swabs Vaginal, anal, and oral swabs Recovered bullets from the Recovered bullets from the

body and/or surrounding body and/or surrounding areaarea

Hand swabs or washings Hand swabs or washings from shooting victimsfrom shooting victims

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Chain of CustodyChain of Custody Chain of custodyChain of custody (CoC), in legal contexts, (CoC), in legal contexts,

refers to the chronological documentation refers to the chronological documentation or or paper trail, showing the seizure, custody, , showing the seizure, custody, control, transfer, analysis, and disposition control, transfer, analysis, and disposition of physical or electronic evidence.of physical or electronic evidence.

Particularly important in criminal cases, the Particularly important in criminal cases, the concept is also applied in civil litigation – concept is also applied in civil litigation – and sometimes more broadly in drug and sometimes more broadly in drug testing of athletes, traceability of food testing of athletes, traceability of food products and to provide assurances that products and to provide assurances that wood products originate from sustainably wood products originate from sustainably managed forests.managed forests.

Police Sketches of CriminalsPolice Sketches of Criminals

Police sketch Police sketch artists will artists will convert a victim convert a victim or eyewitness or eyewitness description to a description to a depiction of the depiction of the suspect. suspect.

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Level Types of Evidence: Level Types of Evidence: Class or IndividualClass or Individual

Class level Class level evidence is a characteristic evidence is a characteristic of evidence that points to a group of of evidence that points to a group of objects or people. Example: new tennis objects or people. Example: new tennis shoes… that lots of people could have.shoes… that lots of people could have.

Individual level Individual level evidence is a evidence is a characteristic of evidence that characteristic of evidence that pinpoints a singular person or object. pinpoints a singular person or object. Example: DNA Example: DNA

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Crime Scene EvidenceCrime Scene Evidence There are many different types of evidence There are many different types of evidence

found at a crime scene. Any of these could be found at a crime scene. Any of these could be a significant piece in solving the crime. The a significant piece in solving the crime. The significance of each piece of evidence is often significance of each piece of evidence is often unknown until after the evidence has been unknown until after the evidence has been bagged, labeled, and sent to the lab.bagged, labeled, and sent to the lab.

For these reasons, forensic scientists treat For these reasons, forensic scientists treat each and every piece of evidence as if it is each and every piece of evidence as if it is vital. Every object at a crime scene is vital. Every object at a crime scene is considered to be significant until toughly considered to be significant until toughly examined.examined.

Types of AnalysisTypes of Analysis ComparisonComparison: : Most types of evidence require a Most types of evidence require a

control with which to be compared (example: control with which to be compared (example: fingerprints, hairs)fingerprints, hairs)

Visual :Visual : Evidence that can be utilized or compared vidence that can be utilized or compared through unaided observation, (example: fingerprints, through unaided observation, (example: fingerprints, tool marks)tool marks)

Microscopic (trace)Microscopic (trace) analysis that evidence that analysis that evidence that must be observed with the use of some type of must be observed with the use of some type of microscope (example: hairs, fibers)microscope (example: hairs, fibers)

ChemicalChemical : If an article of evidence must be subjected If an article of evidence must be subjected to chemical analysis (example: DNA typing, drug to chemical analysis (example: DNA typing, drug screening). Can be Trace Evidencescreening). Can be Trace Evidence

Common Types of Physical EvidenceCommon Types of Physical Evidence DocumentsDocuments. . Any document, handwritten or printed, will be

submitted so that authenticity and source can be determined. These types of analysis are utilized mainly with ransom notes, suicide notes, death threats, and forgeries.

Glass.Glass. Glass panes, particles, or fragments that are found or Glass panes, particles, or fragments that are found or transferred to a person or object involved in a crime may be transferred to a person or object involved in a crime may be substantial evidence. Such evidence, whether broken by a bullet or substantial evidence. Such evidence, whether broken by a bullet or fingerprints, may link a suspect or piece of evidence to a crime scene, fingerprints, may link a suspect or piece of evidence to a crime scene, and be used to deduce cause of breakage or direction of penetration. and be used to deduce cause of breakage or direction of penetration.

FingerprintsFingerprints a mainstay in criminal investigating. When a a mainstay in criminal investigating. When a person touches an article with their bare hands that a print is left person touches an article with their bare hands that a print is left behind. Such prints are called latent prints. with the utilization of behind. Such prints are called latent prints. with the utilization of computers and large databases, identifying a suspect’s prints have computers and large databases, identifying a suspect’s prints have become routine.become routine.

Common Types of Physical EvidenceCommon Types of Physical Evidence

HairsHairs are often found at a crime scene and are are often found at a crime scene and are fairly easy to compare and identify with the use fairly easy to compare and identify with the use of a microscope. Any animal or human hair of a microscope. Any animal or human hair present at the scene could link a person or animal present at the scene could link a person or animal with a crime. With a number of samples to with a crime. With a number of samples to compare, hairs from a crime scene may be compare, hairs from a crime scene may be matched to a suspect with a high degree of matched to a suspect with a high degree of certainty. Upon the discovery of a root or follicle certainty. Upon the discovery of a root or follicle tissue, DNA analysis can provide an exact match.tissue, DNA analysis can provide an exact match.

Body or parts Body or parts are often found in scenes that are often found in scenes that involve the most serious of crime. DNA, involve the most serious of crime. DNA, Anthropology, Odontology can reveal the identity.Anthropology, Odontology can reveal the identity.

Common Types of Physical EvidenceCommon Types of Physical Evidence

Soils, Minerals, Wood, and Other Soils, Minerals, Wood, and Other Vegetative MatterVegetative Matter. . Any items containing Any items containing soil, minerals, wood, or other vegetative matter soil, minerals, wood, or other vegetative matter could link a person or object to a particular could link a person or object to a particular location (for example, soil imbedded in shoes location (for example, soil imbedded in shoes and vault insulation found on garments).and vault insulation found on garments).

FibersFibers are any natural or synthetic fiber are any natural or synthetic fiber transferred which may be useful in establishing transferred which may be useful in establishing a relationship between objects and/or persons. a relationship between objects and/or persons. They may be able to predict if such a fiber They may be able to predict if such a fiber originated from clothes, towels, carpet, or other originated from clothes, towels, carpet, or other sources.sources.

Common Types of Physical EvidenceCommon Types of Physical Evidence

FirearmsFirearms as well as ammunition, are often as well as ammunition, are often important evidence in an investigation. In important evidence in an investigation. In fact, it is often impossible to get a conviction fact, it is often impossible to get a conviction in shooting cases in shooting cases withoutwithout the discovery of the discovery of such evidence.such evidence.

Powder Residue. Powder Residue. A person or item may be suspected of containing firearm discharge residue. The presence and disbursement of powder residue is used to discern if, when, and where a firearm may have been fired.

Common Types of Physical EvidenceCommon Types of Physical Evidence Explosives and petroleum Explosives and petroleum

productsproducts. . These products are devices These products are devices containing an explosive charge, as well as all containing an explosive charge, as well as all objects removed from the scene of an objects removed from the scene of an explosion or fire that are suspected to explosion or fire that are suspected to contain the residues of an explosive material. contain the residues of an explosive material. The placement and appearance of these The placement and appearance of these items is significant in determining where a items is significant in determining where a fire or explosion originated and advanced. fire or explosion originated and advanced. After collection and analysis, the chemical After collection and analysis, the chemical composition of such may be helpful composition of such may be helpful identifying the origin and users of the identifying the origin and users of the substances.substances.

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Common Types of Physical EvidenceCommon Types of Physical Evidence

Impressions and Tool MarksImpressions and Tool Marks. . Impressions include tire markings, shoe Impressions include tire markings, shoe prints, depressions in soft soils, and all prints, depressions in soft soils, and all other forms of tracks, glove and fabric other forms of tracks, glove and fabric impressions, and bite marks in skin or impressions, and bite marks in skin or foodstuffs.foodstuffs.

Drugs.Drugs. Any substance in violation of laws Any substance in violation of laws regulating the sale, manufacture, distribution, regulating the sale, manufacture, distribution, and use of drugs or chemicals will be seized.and use of drugs or chemicals will be seized.

In addition to the large number of illegal drugs In addition to the large number of illegal drugs which are manufactured, sold, and used, a large which are manufactured, sold, and used, a large number of perpetrators committing other crimes number of perpetrators committing other crimes

Common Types of Physical EvidenceCommon Types of Physical Evidence

Paint.Paint. Any paint, wet or dry, may be transferred Any paint, wet or dry, may be transferred from the surface of one object to another during the from the surface of one object to another during the perpetration of a crime. Most paint evidence perpetration of a crime. Most paint evidence originates from crimes involving hit-and-runs. With a originates from crimes involving hit-and-runs. With a control sample to compare a suspected sample, paint control sample to compare a suspected sample, paint can be matched to a vehicle with near 100% certainty.can be matched to a vehicle with near 100% certainty.

Blood, Semen, Saliva, Organs, and Blood, Semen, Saliva, Organs, and other Physiological Fluidsother Physiological Fluids. . All body All body fluids, animal or human, will be subjected to fluids, animal or human, will be subjected to biochemical analysis for determination of identity and biochemical analysis for determination of identity and origin. By examining the amount, color, and origin. By examining the amount, color, and distribution of such fluids, an investigator may able to distribution of such fluids, an investigator may able to make several predictions about what took place at a make several predictions about what took place at a scene.scene.

Collecting EvidenceCollecting EvidenceBag & Tag Bag & Tag

evidence evidence according according to to standard standard operating operating proceduresprocedures

College class College class example videoexample video

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Sample CollectionsSample Collections

Bloody items Bloody items must be must be packaged in packaged in paper bags to paper bags to prevent rotting prevent rotting and mold that and mold that would destroy would destroy the DNA.the DNA.

Sample CollectionsSample Collections Use tweezers / Use tweezers /

forceps to retrieve forceps to retrieve small trace evidence small trace evidence and put it into small and put it into small pill bottles or pill bottles or baggies.baggies.

They should be They should be labeled with all labeled with all relevant information relevant information about the caseabout the case

Sample CollectionSample Collection

You can use a You can use a small piece of small piece of paper to hold paper to hold small dry trace small dry trace evidence. evidence.

For security it For security it should be folded should be folded into the into the “druggist fold”“druggist fold”

Arson SamplesArson Samples

Arson samples Arson samples need to be put need to be put into airtight into airtight containers like containers like paint cans paint cans because the light because the light hydrocarbons will hydrocarbons will evaporate away evaporate away before analysis.before analysis.

Buccal SwabBuccal Swab

The easiest way The easiest way to get DNA to get DNA samples is to rub samples is to rub a Q-Tip around a Q-Tip around inside the inside the cheek /mouth and cheek /mouth and collect epithelial collect epithelial cells. This is used cells. This is used in the lab to make in the lab to make a DNA fingerprinta DNA fingerprint

Changes After DeathChanges After Death

There are 3 major changes to the There are 3 major changes to the body after death when the systems body after death when the systems start to shut down of the start to shut down of the physiological actions.physiological actions.

They are:They are: Algor MortisAlgor Mortis Livor MortisLivor Mortis Rigor MortisRigor Mortis

Algor MortisAlgor Mortis

Algor Mortis is the gradual cooling of the body to ambient temperature after death.

The average is 1 to The average is 1 to 1.5 degrees F loss 1.5 degrees F loss per hour after per hour after death.death.

Rigor MortisRigor Mortis

When you die, your When you die, your muscles become muscles become ridged within 12 – ridged within 12 – 24 hours because 24 hours because the microfibrils the microfibrils lock up.lock up.

It lasts for 36 hours It lasts for 36 hours and then they and then they loosen up due to loosen up due to decay.decay.

Livor MortisLivor Mortis

When you die the When you die the blood stops pumping blood stops pumping and gravity pulls the and gravity pulls the blood to the bottom of blood to the bottom of the body according to the body according to the position you are the position you are in.in.

It shows as a It shows as a discoloration and can discoloration and can be used to see if the be used to see if the body has been moved body has been moved since death.since death.

EntomologistsEntomologists

Entomologists are Entomologists are scientists that study scientists that study insects.insects.

They help forensics They help forensics by helping to by helping to determine the time determine the time of death by judging of death by judging the life stages of the life stages of insects that live in insects that live in the deadthe dead

Collecting ControlsCollecting ControlsControlsControls are samples that help are samples that help

eliminate the innocent bystanders eliminate the innocent bystanders and those not considered as and those not considered as suspects. They include suspects. They include fingerprints, DNA Samples, Hair, fingerprints, DNA Samples, Hair, and other evidence from possible and other evidence from possible suspects or victims for comparison suspects or victims for comparison to evidence. to evidence.

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Search WarrantsSearch Warrants

A search warrant A search warrant is a court order is a court order issued by a magistrate, judge or issued by a magistrate, judge or Supreme Court official that Supreme Court official that authorizes law enforcement officers authorizes law enforcement officers to conduct a search of a person, to conduct a search of a person, location, or vehicle for evidence of a location, or vehicle for evidence of a crime and to confiscate evidence if it crime and to confiscate evidence if it is found. A search warrant cannot be is found. A search warrant cannot be issued in aid of civil process.issued in aid of civil process.

When is a Warrant Required When is a Warrant Required for Evidence Collection?for Evidence Collection?

The The Fourth Amendment to the United Fourth Amendment to the United States Constitution protects Americans States Constitution protects Americans from unreasonable searches by the from unreasonable searches by the government.government.  That means that absent   That means that absent an emergency situation or other legal an emergency situation or other legal exception, a police officer must have a exception, a police officer must have a search warrant before conducting a search warrant before conducting a search of your person or property.search of your person or property.

How to Get a Warrant?How to Get a Warrant?

A judge will only approve a search warrant if A judge will only approve a search warrant if law enforcement is specific as to the items and law enforcement is specific as to the items and location it wishes to search.  Law enforcement location it wishes to search.  Law enforcement must also prove that probable cause exists that must also prove that probable cause exists that a specific item is located in a specific place.a specific item is located in a specific place.

Whether the warrant gets issued or not is up to Whether the warrant gets issued or not is up to the judge's review.  If a judge finds that law the judge's review.  If a judge finds that law enforcement has met its burden of probable enforcement has met its burden of probable cause and has included enough specificity in cause and has included enough specificity in the request for the warrant, then the judge will the request for the warrant, then the judge will issue the search warrant.issue the search warrant.

When is Search Warrant NOT Necessary?When is Search Warrant NOT Necessary? Consent: Law enforcement can request to enter a

person’s home or search a person’s belongings

Plain View Doctrine:  Law enforcement does not need a search warrant to obtain evidence that is in plain

sight.  Emergency Situation: If the police are in hot

pursuit of a felon and follow that alleged felon into a home or other private area then they do not need a warrant to obtain evidence that is in plain sight when they enter the building.

Search Incident to Arrest: Police officers may search the body and immediate surroundings of a person whom they take into custody. 

Review of the Crime Scene AnalysisReview of the Crime Scene Analysis

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