Chapter 1:INTRODUCTION

PRENTICE HALL©2007 Pearson Education, Inc.Upper Saddle River, NJ 07458 1-CRIMINALISTICSAn Introduction to Forensic Science, 9/EBy Richard Saferstein

• forensic (adj)1. pertaining to, connected with, or used in court oflaw or public discussion and debate2. adapted or suited to argumentation; rhetorical• Forensic science (n.)– the application of science to criminal and civil laws.– Emphasizes the application of science to criminaland civil laws that are enforced by police agencies ina criminal justice system.– owes its origins to individuals such as Bertillon,Galton, Lattes, Goddard, Osborn, and Locard, whodeveloped the principles and techniques needed toidentify or compare physical evidence.

Basic Terms• criminalistics (n)– the science dealing with the detection ofcrime and the apprehension of criminals– derived from the German “Kriminalistic”• coined in early 1900’s to attempt to better describe the emerging discipline of “police science”.

What is Science??

• the method of study used in attempting todescribe the physical universe– Identifying repeating patterns from whichgeneral rules can be established• inductive reasoning– extrapolating from the specific to the general– test the general principle by predicting whatwill happen in a specific situation• deductive reasoning

What is Science??

• The scientist obtains– qualitative data by observation– quantitative data by measurement• From this data– attempts to understand and categorize the universe

What is Science??• An experimental result has no standinguntil it is disseminated to the rest of thescientific community– peer-reviewed journal– allows the experiment to be repeated & theresults reproduced• Data is not considered valid untilreproduced by an independent source

Science is Always Changing

• At any point in time, science gives ourbest estimate of how the universe works• New discoveries may refine or refutewhat was considered to be “true”• Understanding changes with newinformation

The Scientific Method

• A framework for testing Hypotheses• Very difficult to prove that an idea,concept or theory is true• We can fail to prove it is false• Absence of info showing a theory to beincorrect leads us to accept it as correctuntil new info is obtained that shows to tobe incorrect

The Null Hypothesis

• The stated idea is untrue• Often assumed in forensic science– “bullet didn’t come from this gun”• Failure to disprove the null hypothesis– provides evidence that the bullet did passthrough the gun

The Scientific Method1. State an hypothesis2. Design an experiment3. Make observations and record data4. Analyze and interpret the data5. Draw a conclusion6. Define the next question

The Scientific Method1.State a hypothesis (What is thequestion?)– “I think that this bullet came from that gun”– we often set out to prove the null hypothesis– formulating a hypothesis is not bias althoughbias can cause the wrong question to beasked• “How did O.J. kill Nicole Brown Simpson & RonGoldman?” (wrong)• “Did O.J. Simpson kill Nicole Brown Simpson & Ron Goldman?” (appropriate)

The Scientific Method

2. Design an experiment to test thehypothesis– compare the bullet microscopically withother test bullets known to have been firedfrom the gun– test bullets are the reference samples to whichthe crime scene bullet will be compared

The Scientific Method3. Make observations and record data– photograph the questioned & referencebullets through the microscope– record the number of features in common• how many• where they are located– a general impression that they were the sameor that they were not the same is notacceptable

The Scientific Method4. Analyze and interpret the data– once data is collected, it must be analyzed– bullet comparison• analysis– scrutinize the marks to determine if any differences between the questioned and known bullet are not relevant to the comparison• interpretation– how many marks need to be similar between the evidence bullet and a test bullet to convince the examiner that the bullet couldn’t have come from another gun

The Scientific Method

5. Draw a conclusion– At the end of the experiment• data must be summarized• a statement of the meaning or the data in the context of the hypothesis must be made– the number of similar marks are sufficient to declare that both bullets came from the same gun– null hypothesis disproved within the limits of the test system

The Scientific Method

6. Define the next question– often the answers obtained generate more questions– the next set of experiments is planned– in forensic science both time and sample are limited• often conclusions must be drawn from only one experiment or limited data• understanding limitations for any particular system is important

History• Mathieu Orfila—the father of forensictoxicology.• Alphonse Bertillion—devised the first scientificsystem of personal identification in 1879.• Francis Galton—conducted the first definitivestudy of fingerprints and their classification.• Leone Lattes—developed a procedure todetermine blood type from dried bloodstains.**• Calvin Goddard—used a comparison microscopeto determine if a particular gun fired a bullet.• Albert Osborn—developed the fundamentalprinciples of document examination.

**Leone Lattes

• In 1901, Dr. Karl Landsteiner discovered theblood can be grouped into different categories.• These blood groups are known as A, B, AB, andO.• Dr Lattes intrigued by Dr. Landsteiner’s discoveryand its realization that these groups could beused for identification, assisted in the creation ofa simple blood test.• This test help identify blood groups from driedblood specimens, which was immediately appliedto Criminalistics.

History• Walter McCrone—utilized microscopy and other analytical methodologies to examineevidence.• Hans Gross—wrote the first paper that concerted scientific applications to forensics describing the application of scientific principles to the field of criminal investigation.• Edmond Locard—incorporated Gross’principles within a workable crime laboratory.• Locard’s Exchange Principle—states that whena criminal comes in contact with an object orperson, a cross-transfer of evidence occurs.

Back in the United States…….• In 1932, J. Edgar Hoover organized the national laboratory, that aimed to offer forensic services to all law enforcement agencies in the country.• The FBI is now the largest Forensic laboratory in the world.• In 1981, the FBI created a Forensic Research and Training Center, dedicated to the development of new technologies to assist in the Forensic investigative process.

In California….

• The oldest crime lab in the United Statesis that of the Los Angeles Police Department in 1923.• Founded by August Vollmer.• August Vollmer’s work eventually created the Collage of Criminalistics at University of California @ Berkley in 1948.

Technical Support• The support provided by crime laboratories can be assigned to five basic services.– Physical Science Unit incorporateschemistry, physics, and geology to identifyand compare physical evidence.– Biology Unit applies the knowledge ofbiological sciences in order to investigateblood samples, body fluids, hair, and fibersamples.– Firearms Unit investigates dischargedbullets, cartridge cases, shotgun shells, and ammunition.

Technical Support– Document Unit provides for handwritinganalysis and other questioned-documentissues.– Photographic Unit applies specializedphotographic techniques for recording andexamining physical evidence.– Some crime laboratories may offer optional voiceprint analysis, evidence collection, and polygraph administration.

Technical Support• Optional Services by Full-Service Labs– Toxicology Unit examines body fluids and organsfor the presence of drugs and poisons.– Latent Fingerprint Unit processes and examinesevidence for latent fingerprints.– Polygraph Unit conducts polygraph or lie detectortests.– Voiceprint Analysis Unit attempts to tie a recordedvoice to a particular suspect.– Evidence-Collection Unit dispatches speciallytrained personnel to the crime scene to collect andpreserve physical evidence.

Special Forensic Science Services

• A number of special forensic science services are available to the law enforcement community to augment the services of the crime laboratory.

• These services include forensic pathology, forensic anthropology, forensicentomology, forensic psychiatry, forensic odontology, computer science, andforensic engineering.

Special Forensic Science Services

• Forensic Pathology involves theinvestigation of unnatural, unexplained,or violent deaths.

– Forensic pathologists in their role as medicalexaminers or coroners are charged withdetermining cause of death.

– The forensic pathologist may conduct anautopsy which is the medical dissection andexamination of a body in order to determinethe cause of death.

Special Forensic Science Services• After a human body expires there are severalstages of death.– Rigor mortis results in the shortening of muscletissue and the stiffening of body parts in the position at death (occurs within the first 24 hours and disappears within 36 hours).– Livor mortis results in the settling of blood in areas of the body closest to the ground (beginsimmediately on death and continues up to 12 hours).– Algor mortis results in the loss of heat by a body (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)

Special Forensic Science Services• Forensic Anthropology is concernedprimarily with the identification andexamination of human skeletal remains.

• Forensic Entomology is the study ofinsects and their relation to a criminalinvestigation, commonly used to estimatethe time of death.

• Forensic Psychiatry is an area in whichthe relationship between human behaviorand legal proceedings is examined.

Special Forensic Science Services

• Forensic Odontology involves using teethto provide information about theidentification of victims when a body isleft in an unrecognizable state; alsoinvestigates bite marks.• Forensic Engineering is concerned withfailure analysis, accident reconstruction,and causes and origins of fires orexplosions.• Forensic Computer Science involves theexamination of digital evidence.

Skills of a Forensic Scientist• A forensic scientist must be skilled in applyingthe principles and techniques of the physicaland natural sciences to the analysis of the manytypes of evidence recovered during a criminalinvestigation.• A forensic scientist may also provide expertcourt testimony.• An expert witness is an individual whom thecourt determines possesses knowledge relevantto the trial that is not expected of the averageperson.

Skills of a Forensic Scientist

• The expert witness is called to evaluateevidence based on specialized trainingand experience that the court lacks theexpertise to do.

• The expert expresses an opinion as to thesignificance of the findings.

• Forensic scientists participate in traininglaw enforcement personnel in the properrecognition, collection, and preservationof physical evidence. (web-extra)

The Law and the Analyst

• The criminalist has no function without the judicial system

• The analyst’s job:– provide scientific info to the legal community– translate the story the evidence has to tell

• Analysis is done only at the behest ofsomeone seeking to introduce the evidence into a court of law (prosecution or defense)

Circumstantial Evidence

• All physical evidence is circumstantial

– its involvement has not been substantiated by an eyewitness– often the term circumstantial evidence carries the connotation of untrustworthiness– eyewitness evidence tends to be considered conclusive

Circumstantial vs. Eyewitness

Scenario:

You are camping in a cabin deep in the woods in the mountains during the winter. Several feet of snow cover the ground. You hear a sound in the middle of the night and go to the window to see what it is. The moon is new so it is almost pitch dark.

Circumstantial vs. Eyewitness

You see a quickly moving shadow that almost blends into the snow.

• Is it a polar bear?• Is it a burglar dressed in white?

Circumstantial vs. Eyewitness

The next morning find…

• clear snowshoe tracks• the lock on your tool shed is hanging open• some of your tools are missing

Circumstantial vs. Eyewitness

Which is more convincing?

• midnight glimpse– eyewitness evidence• prints in the snow– circumstantial evidence

The Frye Standard

• The Frye v. United States decision set guidelines for determining the admissibility of scientific evidence into the courtroom.

• To meet the Frye standard, the evidence inquestion must be “generally accepted” by the scientific community.

Frye Not Absolute

• In the 1993 case of Daubert v. MerrellDow Pharmaceutical, Inc., the U.S. Supreme Court asserted that the Frye standard is not an absolute prerequisite to the admissibility of scientific evidence.

• Trial judges are ultimately responsible for the admissibility and validity of scientific evidence presented in their courts, as well as all expert testimony.

The Daubert Criteria

• In Daubert, the Supreme Court offeredsome guidelines as to how a judge cangauge scientific evidence:

1) Whether the scientific technique ortheory can be (and has been) tested.2) Whether the technique or theory hasbeen subject to peer review andpublication.3) The technique’s potential rate of error.

The Daubert Criteria

4) Existence and maintenance ofstandards controlling the technique.

5) Whether the scientific theory or method has attracted widespread acceptance within a relevant scientific community.