Forensics: Exam 1 Part 1

Forensic Science definition

application of science to criminal and civil laws

Mathieu Orfila

father of forensic toxicology

Alphonse Bertillon

Devised the 1st scientific system of personal identification in 1879

Francis Galton

Conducted the first definitive study of fingertips and their classification

Leone Lattes

Developed a procedure to determine bloody type from dried bloodstains

Calvin Goddard

Refined the technique of determining if a particular gun fired a bullet by using the comparison microscope

Albert Osborne

developed the fundamental principles of document examination

Walter McCrone

Advanced the field of microscopy and its application to examining evidence

Hans Gross

Wrote the first treatise describing the application of scientific principles to the field of criminal investigation

Edmond Locard

incorporated Gross' principals within a workable crime lab

Locard's Exchange Principle

states that when a criminal comes in contact with an object or person, a cross-transfer of evidence occurs

Why are there an ever increasing number of crime labs?

supreme court decisions in the 1960's responsible for police placing greater emphasis on securing scientifically evaluated evidence, crime labs inundated with drug specimens due to accelerated drug abuse, and the advent of DNA prolifing

How many current crime labs are there?

411 - federal, state, county, and municipal

Physical Science Unit

incorporates the principles of chemistry, physics, and geology to identify and compare physical evidence (drugs, glass, paint, explosives, and soil)

Biology Unit

applies the knowledge of biological sciences in order to investigate blood samples, body fluids, hair, and fiber samples

Firearms Unit

investigates discharged bullets, cartridge cases, shotgun shells, and ammunition. Tool mark comparisons may also be made in this unit

Document Examination Unit

Provides handwriting analysis and other reproduction processes; ink and paper analysis; forgery and authenticity. Also analyzes indentations, obliterations, erasures, and burned or charred documents.

Photography Unit

applies specialized photographic techniques for recording and examining physical evidence

What are the five basic services provided by crime labs?

physical, biology, firearms, document, and photography

Toxicology Unit

examines body fluids and organs for the presence of drugs and poisons

Latent Fingerprint Unit

processes and examines evidence for latent fingerprints

Polygraph Unit

conducts polygraph or lie detector tests

Voiceprint Analysis Unit

attempts to tie a recorded voice to a particular suspect

Crime Scene Investigation Unit

dispatches specially trained personnel to the crime scene to collect and preserve physical evidence

What are the five optional services by full-service labs?

toxicology, fingerprint, voiceprint, polygraph, and crime-scene investigation

Functions of a forensic scientist

must be skilled in applying the principals and techniques of the physical and natural sciences to analyze the many types of evidence that may be recovered during a criminal investigation - scientific method, provide expert court testimony

Scientific Method

formulate a QUESTION worthy of an investigation, formulate a reasonable HYPOTHESIS to answer question, test the hypothesis through EXPERIMENTATION, upon VALIDATION the hypothesis becomes suitable as SCIENTIFIC EVIDENCE

What is an expert witness

An individual whom the court determines to possess knowledge relevant to the trial that is not expected of the average lay person

What is the role of an expert witness

gets called on to evaluate evidence based on specialized training and experience that the court lacks the expertise to do and the expert will then express an opinion as to the significance of the findings

The Frye vs U.S

decision set guidelines for determining the admissibility of scientific evidence into the courtroom

How to meet the Frye standard

the evidence in question must be "generally accepted" by the scientific community

Frye not absolute

in the 1993 case of Daubert vs. Merrell Dow Pharmaceutical Inc., the US supreme court asserted that the Frye standard is not an absolute prerequisite to the admissibility of science evidence

What occured in the Daubert vs. Merrell Dow Pharmaceutical Inc case?

trial judges were said to be ultimately responsible as "gatekeepers" for the admissibility and validity of scientific evidence presented in their courts, as well as expert testimony

In Daubert, the supreme court offered some guidelines as to how a judge can gauge the reliability of scientific evidence:

whether the scientific technique/theory can be or has been tested, whether the technique of theory has been subject to peer review and publication, the techniques potential rate of error, existence and maintenance of standards controlling the tech. operation, and whether the scientific theory/method has attracted widespread acceptance within a relevant scientific community

Kumno Tire Co. Ltd vs. Carmicheal

determined that the judge acts as a "gatekeeper" not only for scientific testimony, but any testimony

Melendez-Diaz vs Massachusetts

determined that an expert witness must appear in person to provide testimony in court so that the defense has an opportunity to cross-examine the witness

Evidence Collection Training

Many crime laboratories have "evidence technicians," trained by the crime lab staff, on 24-hour call for evidence collection at crime scenes.

Training ensures all pertinent evidence will be recognized and collected properly.

Where no formal training exists, familiarity can be gained through lectures, tours of the lab, and evidence collection manuals.

What special forensic science services are available to the law enforcement community?

forensic psychiatry, forensic odontology, forensic engineering, and forensic computer and digital analysis

Forensic Psychiatry

relationship between human behavior and legal proceedings is examined

Forensic odontology

involves using teeth to provide information about the identification of victims when a body is left in an unrecognizable state; also investigates bite marks - though has become a controversial method of anaylsis

Forensic engineering

concerned with failure analysis, accident reconstruction, and causes and origins of fires or explosions

Forensic computer and digital anyalsis

involves the identification collection, preservation, and examination of digital evidence

Physical Evidence

Any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator

Purpose of examining physical evidence

Identification and comparison analysis

Identification - what does it require

the object is to determine the physical and chemical identity with as near absolute certainty as existing analytical technique will permit

• 1st: the adoption of testing procedures that give characteristic results for specific standard materials

-2nd: the number and type of tested needed to identify a substance be sufficient to exclude all other substances

What are common types of identification

drugs, gasoline in residues recovered from debris of a fire, or the nature of explosive residues(dynamite/TNT), blood, semen, hair, or wood

Comparison

important for determining whether or not a suspect specimen and a standard/reference specimen have a common orgin

What is the 2 step procedure for forensic comparison

combination of select properties are chosen from the suspect and the reference/standard specimen for comparison; once the examination has been completed, the forensic scientist must be prepared to render a conclusion with respect to the orgins

Role of Probability

To comprehend the evidential value of a comparison, one must appreciate the role that probability has in ascertaining the origins of two or more specimens.

Probability

the frequency of occurrence of an event - flipping a coin/with many analytical processes, exact probability is impossible to define

Individual characteristics

properties of evidence that can be attributed to a common source with an extremely high degree of certainty - in all cases it is not possible to state with mathematical exactness the probability that the specimens are of a common origin, but it can only be concluded that this probability is so high as to defy mathematical calculations or human comprehension

What are examples of individual characteristics?

matching ridge characteristics of 2 fingerprints, comparison of random striation markings on bullets or tool marks, comparison of random patterns in tire or footwear impressions, handwriting, bag striation marks, fitting together irregular edges of broken objects

Class characteristics

evidence associated only with a group

Examples of class characteristics

paint, glass, fibers, drugs, and items without unique distinguishing characteristics

Class Evidence

one of the current weaknesses of forensic science is the inability of the examiner to assign exact or even approximate probability values to the comparison of most class physical evidence, few statistical data available - mass produced world, significance of physical evidence is ultimately determined in the court room

Example of class evidence difficulty?

what is the probability that a nylon fiber originated from a particular sweater, or that a paint chip came form a suspect car in a hit-and-run

Crossing Over

just when an item of physical evidence crosses the line that distinguishes class from individuals evidence is a difficult question to answer and leads to heated debate and honest disagreement among forensic scientists

Chances are low of encountering 2 distinguishable items of physical evidence at a crime scene that actually originated from different sources - how many handwriting characteristics tie a person to a signature, and how many color layers individualize a paint chip to a single car?; what is the task of the forensic scientists?

find as many characteristics as possible to compare one substance to another

Natural vs. Evidential limits

There are practical limits to the properties and characteristics the forensic scientist can select for comparison.

Natural Variations

No two things are alike in every detail. Modern analytical techniques have become so sophisticated and sensitive that these, found in objects, become almost infinite

Forensic Databases: a national fingerprint and criminal history system maintained by the FBI

Integrated Automated Fingerprint Identification System (IAFIS)

Forensic database: enables federal, state, and local crime labs to electronically exchange and compare DNA profiles

Combined DNA Index System (CDIS)

Forensic Database: are emerging to identify close relatives using DNA profiles: contain samples that are processes by commercial genealogy companies and uploaded by private citizens

Genealogy databases (GEDmatch)

Forensic Database: allows firearm analyst to acuire, digitize, and compare markings made by a firearm on bullets and cartridge casings

The National Integrated Ballistics Information Networks (NIBIN)

Forensic database: contains chemical and color info pertaining to original automotive paints

The International Forensic Automotive Paint Data Query (PDQ)

Forensic database: shoe print database

SICAR - shoe print image capture and retrieval

What are first responding police officers responsible for?

acquiring medical attention for injured victims (avoid disturbing evidence and approach victim by an indirect route), detaining any potential victims and suspects (take statements), securing the crime scene, and calling for additional personnel needed (other officers and/or forensic investigators)

Securing the crime scene can include

determining the perpetrators possible entry and exit, having a detailed log of personal movements in and out of the crime scene, and no eating, drinking, smoking, or littering

Searching the crime scene

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

Recording methods

photography, sketches, notes are the 3 methods that should be employed, however the personnel and monetary limitations may limit the utilization of photography at every crime scene

Crime Scene notes

begins with the investigator reporting to the scene. Includes identity of the person who contacted the investigator, time of contact and arrival at the crime scene, preliminary case info, and personnel present on arrival and those being contacted, contain a personnel log of all observations made by the investigator and the time the observation were made

Digital Photography

made when a light-sensitive microchip captures light on each of millions of tiny picture elements called pixels.

Advantages of digital photograhy

the ability to observe images immediately after taking them, ensuring important photographs are clear and show the best detail, and the ability to preserve the details of the crime scene exactly as they were found

How should crime scene photography be captured

the overall scene, then work down to individual pieces of evidence that the jurors in the trial will be able to easily relate back to the larger scene

What are the 4 minimum photographs required at a crime scene

overview photograph, medium-range, close-up, and close-up with a measurement scale

Overview photographs

the entire scene and surrounding area, including points of entry and exit - are taken first. Include a visual tag, an object recorded in multiple overview photographs, to help visually piece the scene together

Medium range photographs

show the layout of smaller significant areas of the crime scene. Taken with evidence markers in place to show the spatial relationship between and among pieces of evidence. Include at least 1 photo of the "center" of the scene. In violent crimes, this usually involves the site where the victim was found

Close-up photographs

taken last and show great detail. Taken at a 90 degree angle to the object with and without evidence markers and scales. Scales should be placed as close to the evidence as possible without affecting it in any way

What are the most important close-up photographs?

those depicting injuries and weapons lying near a body

After the body is removed from the scene, what should happen?

the surface beneath the body should be photographed

Videotaping crime scenes

Combines photography and notes. Must include overview, medium range, and close up images. Important that only one person narrates and no side conversations are captured on the video. Digital camera photos are still required

Body worn cameras

cased with conflicting eyewitness accounts prompted calls for these for police. Have at least 1 microphone and internal data storage, and are efficient for collecting evidence and recording crime scenes

Sketching the crime scene

clearly show the layout of a crime scene, illustrate the relationship in space of all signifiant items/features, clarify objects and features already described in notes or shown in photographs, show measurements over long distances (topgraphy for outdoor scenes), and depict possible paths of entry, exit, and movement throughout the scene.

The rough crime scene sketch

created at the crime scene, contains accurate depiction of the dimensions of the scene, and shows the location of all pertinent objects and features. Not drawn to scale but should show the accurate measurements of the distances of sign. objects or scene boundaries

All rough sketches include

-Title block with information on the case, crime scene, and person creating the sketch

-Legend with identity and dimensions of objects in the sketch

-Compass showing the North direction

-Body containing the sketch itself

The finished crime scene sketch

created from the information in rough sketch, but it is drawn to scale with care and concern for appearance. The current standard method utilized computer aided drafting programs to create the finished sketch. (CAD programs allow for the creation of 3-D sketches)

Entering the crime scene (search)

the walkthrough is the initial survey of the crime scene - perpetrators point of entry and exit are located and the indirect path is taken to the center of the crime scene. Obvious items of evidence are located and documented, and the conditions of the scene are observed and recorded

Line strip search pattern

One or two investigators start at the boundary of the crime scene and search in straight lines across to the other side of the crime scene.

Grid search pattern

Two or more investigators form a grid by searching in line patterns that overlap and are perpendicular to each other.

Spiral search pattern

one investigator searches in a spiral path from the center of the crime scene to the boundary or vice versa

Wheel/ray search pattern

Several investigators search in straight lines from the center to the boundary (outward) or from the boundary to the center (inward).

Quadrant/zone search pattern

The crime scene is divided into smaller sections (zones). One or more investigators are assigned to search each zone.

Vehicle searches

search interior and exterior, may searched at the crime scene, police department, or crime lab