1 forensic science powerpoint chapter 01 here we stand, what a

Chapter 1Chapter 1CRC Press: Forensic Science, James CRC Press: Forensic Science, James

and Nordby, 3rd Editionand Nordby, 3rd Edition 11

Forensic ScienceForensic Science

An Introduction to Scientific and An Introduction to Scientific and Investigative TechniquesInvestigative Techniques

Stuart H. James and Jon J. NordbyStuart H. James and Jon J. Nordby

22Chapter 1Chapter 1CRC Press: Forensic Science, James CRC Press: Forensic Science, James

and Nordby, 3rd Editionand Nordby, 3rd Edition

Chapter 1Chapter 1

Here We Stand: Here We Stand:

What a Forensic Scientist does.What a Forensic Scientist does.

Chapter Author: Jon J. NordbyChapter Author: Jon J. Nordby

Presentation created by Greg Galardi, Peru, NebraskaPresentation created by Greg Galardi, Peru, Nebraska

Edited by Stuart H. James, Fort Lauderdale, Florida andEdited by Stuart H. James, Fort Lauderdale, Florida and

Dan Mabel, Richmond, VirginiaDan Mabel, Richmond, Virginia



Requirements of a Forensic Requirements of a Forensic ScientistScientist

• Ability to reason during times when Ability to reason during times when human emotion may attempt to human emotion may attempt to override rationalityoverride rationality

• Ability to be rational in applying tenets Ability to be rational in applying tenets of forensic science to real life human of forensic science to real life human situations situations

• Ability to address life’s grimmest Ability to address life’s grimmest realities while maintaining human realities while maintaining human feelingsfeelings



Forensic ScientistsForensic Scientists

• May recover human remainsMay recover human remains

• Identify human remainsIdentify human remains

• Document the cause of human deathDocument the cause of human death

• Assist in criminal investigations Assist in criminal investigations through scientific analysis of evidencethrough scientific analysis of evidence




• Contribute scientific reliability in court, Contribute scientific reliability in court, which maywhich may• Ensure the guilty receive punishmentEnsure the guilty receive punishment• Free innocent peopleFree innocent people• Provide a method to correlate a Provide a method to correlate a

measurement of scientific reliability with a measurement of scientific reliability with a specific facet of forensic sciencespecific facet of forensic science



Law and Forensic ScienceLaw and Forensic Science

• Forensic scientists are independent Forensic scientists are independent finders of factfinders of fact

• Most operate under police jurisdiction Most operate under police jurisdiction or administrationor administration

• Have a duty to strike a balance between Have a duty to strike a balance between duties of job and results of testsduties of job and results of tests

• Must be committed to ethical behaviorMust be committed to ethical behavior• Must be able to distinguish reliable Must be able to distinguish reliable

from unreliable scientific practicefrom unreliable scientific practice



Law and ScienceLaw and Science

• Forensic Scientists shouldForensic Scientists should• Use all relevant testing to discern truthUse all relevant testing to discern truth• Define “scientific error” categorically, not Define “scientific error” categorically, not

personallypersonally• Be adaptable and advance the common Be adaptable and advance the common

goodgood• Understand that courts often resolve Understand that courts often resolve

applications of the legal issues applications of the legal issues surrounding forensic sciencesurrounding forensic science



Lawyers and Forensic ScientistsLawyers and Forensic Scientists

• Both lawyers and forensic scientists Both lawyers and forensic scientists have legal and moral obligationshave legal and moral obligations

• Both focus on determining the truth or Both focus on determining the truth or circumstances surrounding a crimecircumstances surrounding a crime

• Law is outcome based, while science is Law is outcome based, while science is justification basedjustification based

• Evidence and it’s admissibility play a Evidence and it’s admissibility play a critical role in determining truthcritical role in determining truth



Theoretical Natural Sciences and Theoretical Natural Sciences and Practical Forensic SciencesPractical Forensic Sciences

• Forensic Scientists, unlike their Forensic Scientists, unlike their counterparts, must become familiar counterparts, must become familiar with lawyers and the lawwith lawyers and the law

• Forensic Scientists must combine Forensic Scientists must combine scientific skills with a sworn duty to the scientific skills with a sworn duty to the public goodpublic good

• Forensic Science = Public ScienceForensic Science = Public Science



Natural vs. Forensic ScienceNatural vs. Forensic Science

• Natural SciencesNatural Sciences• TheoreticalTheoretical• Pure KnowledgePure Knowledge• OrderlyOrderly• PristinePristine• ControlledControlled• GeneralGeneral• Covering LawsCovering Laws• PredictionsPredictions• CertainCertain

• Forensic ScienceForensic Science• PracticalPractical• Applied to problemsApplied to problems• DisorderlyDisorderly• ContaminatedContaminated• ChaoticChaotic• SpecificSpecific• ApproximationsApproximations• ConjecturesConjectures• UncertainUncertain



Theoretical Natural Sciences and Theoretical Natural Sciences and Practical Forensic SciencesPractical Forensic Sciences

• Ceteris Paribus LawsCeteris Paribus Laws• ““Other things being equal” Other things being equal”

• Scientists use the Scientific Method,Scientists use the Scientific Method,• Provide identical method of inquiryProvide identical method of inquiry• Focus on scientific reliabilityFocus on scientific reliability• Establish a series of steps of investigationEstablish a series of steps of investigation



Reliable Method of Inquiry: The Reliable Method of Inquiry: The Common Ground of Theoretical Common Ground of Theoretical

and Forensic Scienceand Forensic Science• Reliable methods possess Reliable methods possess

characteristics of:characteristics of:• IntegrityIntegrity• CompetenceCompetence• Defensible TechniqueDefensible Technique• Relevant ExperienceRelevant Experience



Forensic Experts and their roleForensic Experts and their role

• Scientists explain phenomena by Scientists explain phenomena by starting with data surrounding an event starting with data surrounding an event or inquiryor inquiry

• Suggest explanatory connections to Suggest explanatory connections to pursue and testpursue and test

• Distinguish data that are evidence from Distinguish data that are evidence from data that is coincidentaldata that is coincidental

• Share a fundamental approach in Share a fundamental approach in common with other scientistscommon with other scientists



Role of the Forensic ExpertRole of the Forensic Expert

• Expert witnesses can only be declared by a Expert witnesses can only be declared by a judgejudge

• Forensic Scientists remain a scientist first Forensic Scientists remain a scientist first and are an expert secondary to that roleand are an expert secondary to that role

• Give expert opinions within area of expertiseGive expert opinions within area of expertise• Used when facts are unclear in a case orUsed when facts are unclear in a case or• When clarification of procedures is needed When clarification of procedures is needed

oror• When a jury needs assistance in making an When a jury needs assistance in making an

educated decisioneducated decision



Scientific MethodScientific Method

• Features implementation of reliable methodsFeatures implementation of reliable methods• Distinguishes evidence from ambiguityDistinguishes evidence from ambiguity• Allows ranking of alternative results by a Allows ranking of alternative results by a

principle basic to that scienceprinciple basic to that science• Allows for certainty considerations based Allows for certainty considerations based

upon ranking of alternative resultsupon ranking of alternative results• Disallows hypotheses more extraordinary Disallows hypotheses more extraordinary

than facts themselvesthan facts themselves



Scientific MethodScientific Method

• Pursues general impressions to the Pursues general impressions to the specific level of detailspecific level of detail

• Pursues testing by breaking Pursues testing by breaking hypotheses (alternative explanations) hypotheses (alternative explanations) into their smallest logical components, into their smallest logical components, one part at a timeone part at a time

• Allows tests either to prove or to Allows tests either to prove or to disprove alternative explanations disprove alternative explanations (hypotheses)(hypotheses)




• Reason from a given set of results Reason from a given set of results (crime scene)(crime scene)

• To probable explanation (link to To probable explanation (link to perpetrator)perpetrator)

• And explain these results to justify they And explain these results to justify they are better than other alternative are better than other alternative explanationsexplanations




• Must attach some degree of certainty to Must attach some degree of certainty to their worktheir work

• Should not omit larger issues which Should not omit larger issues which could lead to a false opinion could lead to a false opinion

• Leave out the precision of mathematics Leave out the precision of mathematics and probability theoryand probability theory

• Must develop an intellect not too sure Must develop an intellect not too sure of what must remain uncertain, not too of what must remain uncertain, not too certain of what must remain sure.certain of what must remain sure.

1 forensic science powerpoint chapter 01 here we stand, what a

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