mr. edwin osebe agasa. expert witnesses types of evidence forensic victimology ballistics dna...

Mr. Edwin Osebe Agasa

EXPERT WITNESSES TYPES OF EVIDENCE FORENSIC VICTIMOLOGY BALLISTICS DNA ANALYSIS FINGER-PRINT ANALYSIS

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Hate evil, love good; maintain justice in the courts (Amos 5:15).

Admissibility of Tests, Evidence and Testimony A major issue of concern that crosses all fields of

forensic science involves the existence of legal standards for the admissibility of forensic tests and expert testimony.

One legal standard for the admissibility of a forensic test is Frye v United States, which states that the forensic technique in question must have “general acceptance” by the scientific community.

Rule 702 of the Federal Rules of Evidence regulates the admissibility of expert testimony in regard to a test or discipline.

Daubert v Merrell Dow Pharmaceutical, Inc states that the decision about the admissibility of scientific evidence resides with the judge hearing the case.

3Hate evil, love good; maintain

justice in the courts (Amos 5:15).

An expert witness is a witness who gives evidence designed to assist the court based on the witness’s specialized training, study, or experience.

In contrast to a “fact witness,” who is usually only able to relate the facts of the issue at hand as he/she observed them, an “expert witness,” because of his/her specific expertise within a particular discipline, is also able to offer opinions regarding issues that relate to the specific discipline.

Hate evil, love good; maintain justice in the courts (Amos 5:15). 4

In order to be recognized as an expert witness, the witness must be officially qualified, or recognized as an expert, by the court.

Usually this involves a legal process referred to as voir dire, wherein the credentials, training, experience, etc. are presented to the court via questions/answers between an attorney and the witness.

So long as this presentation is acceptable to both sides and the judge, a witness may be qualified to testify as an expert in a particular field.


Helpfully, Eggleston (1983) argues that the expert’s role may be satisfied by performance of four separate yet related functions:

Generalizing from experience; Acting as librarian; Acting as statistician; and Acting as advocate.


Evidence not forget. It is not confused by the excitement of the moment.

It is not absent because human witnesses are.

It is factual evidence. Physical evidence cannot be wrong; it

cannot perjure itself; it cannot be wholly absent. Only its interpretation can err (Dr. Paul Kirk).



Direct Evidence “Direct” evidence is evidence that

establishes a particular fact without the need to make an inference in order to connect the evidence to the fact.

Direct evidence proves or disproves a fact directly. Perhaps the most commonly-known type of direct evidence is eyewitness testimony, where a witness describes exactly what she saw, heard, or experienced.


Fragmentary Evidence Fragmentary evidence—now popularly

referred to as latent, or trace evidence. Locard explains that Fragmentary Evidence

focuses on the exchange of molecular and chemical content, and working with trace biological samples—hair, fibers, blood, fingerprints, footwear impressions.


Circumstantial Evidence “Circumstantial” evidence, on the other

hand, requires an inference to be made in order to establish a fact.


Documentary Evidence Documentary evidence” is a type

of evidence used at trial to show certain information to the jury.

Although the phrase “documentary evidence” is sometimes used only to refer to wills, trusts, or invoices, any type of evidence that presents recorded information in some way can be considered “documentary.”

Written documents, photographs, videos, sound recordings, and print.


Physical Evidence Physical evidence usually involves objects

found at the scene of a crime. Physical evidence may consist of all sorts of prints such as fingerprints, footprints, handprints, tidemarks, cut marks, tool marks, etc.

Examination of some physical evidence is conducted by making impressions in plaster, taking images of marks, or lifting the fingerprints from objects encountered.


Trace Evidence The screening for and the analysis of

ignitable liquids, fibers, soil, glass, paint, hair, explosives, footwear, tire impressions and miscellaneous evidence.


Forensic Victimology: The scientific study of victims for the purposes of addressing investigative and forensic issues.

Lifestyle Exposure: The potentially harmful elements that exist in a victim’s everyday life as a consequence of biological and environmental factors, as well as past choices.

Situational Exposure: The amount of actual exposure or vulnerability experienced by a victim to harm, resulting from his or her environment and personal traits at the time of victimization.



Commonly, forensic victimologists serve investigations and eventual court proceedings with reports and testimony by endeavoring to:

1. Assist with contextualizing allegations of victimization;

2. Help support or refute allegations of victimization;

3. Help establish the nature of victim exposure to harm or loss;

4. Assist with the development of offender modus operandi and motive;

5. Help establish an investigative suspect pool; 6. Assist with the investigative linkage of

unsolved cases.


Victim lifestyle exposure is concerned with studying the potentially harmful elements that exist in a victim’s everyday life as a consequence of biological and environmental factors, as well as past choices.

As defined in Petherick and Turvey (2008, p. 383), victim lifestyle exposure is “the amount of exposure to harmful elements experienced by the victim and resulting from the victim’s usual environment and personal traits.”

Victimology requires an investigation and assessment of the victim’s personality, and his or her personal, professional, and social environment (Turvey, 2008).


The causal link between a victim’s lifestyle and his or her victimization is not always clear. The reason is that it is difficult to reconcile just how much influence any one lifestyle factor has on the criminal situation.

Generally, lifestyle factors can influence harm to the victim in three ways: by creating a perceived conflict with an offender, by increasing the victim’s presence around offenders or those predisposed toward criminality, or by enhancing an offender’s perception of victim vulnerability.


To accurately determine a specific victim’s lifestyle exposure, one needs to assess the victim’s harm in the context of his or her specific lifestyle and personality traits.

For investigative purposes, lifestyle factors must be questioned as to how, specifically, they contributed to harm.


For example, statistics indicate that college students are at higher risk of victimization (Fisher et al., 1998).

One might assume that the mere situation of being a college student increases exposure to harm.

This assumption is not necessarily correct; not all college students are identical.

Some expose themselves to more harm than others through their drug and alcohol use, routine, sexual activity, and a number of other factors.


Victim situational exposure is the amount of actual exposure or vulnerability experienced by the victim to harm, resulting from his or her environment and personal traits, at the time of victimization (Petherick and Turvey, 2008).

Consider the issue of alcohol. Being a person who routinely becomes intoxicated increases one’s lifestyle exposure to the many harmful effects of alcohol, which will be mentioned shortly.

However, unless a victim is actually intoxicated at the time of victimization, it does not necessarily raise her situational exposure.


It is possible to have a high lifestyle exposure related to alcohol abuse, but a low situational exposure from lack of alcohol use or abuse at the time of victimization. The opposite is also true.

Consider also the issue of firearms. Being a person who does not own a firearm, use a firearm, have one in one’s home, or live with or interact with those that do decreases one’s overall lifestyle exposure to the harmful effects of firearms.


However, if a victim is at a shooting range for the first time is accidentally shot, it must be recognized that his incident exposure to harm from firearms was quite high at the time of victimization.

This is true even if he was not participating or holding a gun, given his situational proximity to multiple loaded firearms being discharged by multiple persons of varying skill levels.


Victimological information should be gathered objectively and consistently, and then used to describe or evaluate victims and their circumstances so that judges and juries are privy to information that may be relevant to their decisions.

In this context, direct questions must be asked: Was the victim using drugs?

Does the victim have a history of falsely reporting crime?

What was the extent of the victim’s physical injuries? Was the victim conscious during the attack? Does the victim have a history of taking rides from

strangers or letting strangers into his or her home? Does the victim lock the door at night?


The judge, who determines what is legally admissible,

decides the issue of relevance for these and similarly themed questions.

Then, the judge makes a ruling: sometimes everything about a victim is admissible, sometimes nothing, and sometimes the court “splits the baby” by admitting a percentage of victim information.

The more accurate and complete the victim information provided, the clearer the context of the crime.


Blood and other bodily fluids can be transferred from one person to another, or identified at crime scenes.

Forensic serologists can perform tests to determine if a suspicious fluid or stain is saliva, semen or blood.

Tests are available to determine if the evidence, such as blood, is of human origin.

Once it is identified as human, then DNA (deoxyribonucleic acid) testing can be attempted.



Forensic DNA testing is sometimes referred to as “DNA fingerprinting.”

With the exception of identical twins, no two individuals’ DNA is exactly alike.

Like other comparison tests within the forensic sciences, a standard sample from a suspect is required in order to make a comparison.


Alternatively, if a known standard is not available (for example, when an unidentified body is thought to be a particular person, but no standard of that person is available for comparison), then samples from close relatives (parents, siblings) can be used.

Our genetic information is contained within structures called genes, which are made-up of DNA. Each gene can be considered a template for the production of a specific protein.


Proteins are substances that perform all sorts of functions within our bodies; without them, life would be impossible.

Our genes are mostly contained within structures called chromosomes, which reside within the nucleus of our cells.


A few genes are present within mitochondria, a subcomponent of cells that reside outside of the nucleus within the cytoplasm of our cells.

All humans (excluding those with certain genetic abnormalities) have a total of 46 chromosomes within each of their nucleated cells (cells that have a nucleus).


It should be mentioned here that most blood cells (normal red blood cells) do not have nuclei, although white blood cells do have nuclei, so the DNA testing performed on blood relies on the DNA contained in the white blood cells.

Almost all other cells of the body do have nuclei. The 46 chromosomes are composed of 22 pairs

of “autosomes” (numbered 1–22) and a pair of “sex chromosomes.” In females, there are two X chromosomes, while in males, there is a single X chromosome and a single Y chromosome.


Each person receives 23 chromosomes (22 autosomes and one sex chromosome) from their mother and 23 chromosomes from their father.


Forensic DNA experts rely on the fact that in many different locations within human chromosomes, there are sequences of DNA base-pairs that demonstrate a great deal of variation from one individual to another.

If a forensic scientist is able to evaluate and identify the exact base-pair sequences from a sufficient number of these variable regions, then from a statistical standpoint, the forensic scientist is able to determine a unique “DNA profile” for any individual evaluated.



A “blood spot”card from an autopsy, used topreserve a blood sample forpotential DNA testing

Dr. Locard put the analysis of handwriting on a firmer footing, systematized the analysis of the dust in the clothes of suspects, invented a modified method of analyzing blood stains, and invented poroscopy, whereby the pores in the papillary ridges of fingerprints are used as a means of identification.



It is true that Dr. Locard concerned himself chiefly with organizing and systematizing methods of analyzing prints, traces, and stains.

He wrote extensively on how to identify and individuate dust, how to identify and individuate fingerprints, how to analyze and interpret handwriting, how to analyze and interpret bloodstains, and the like.


It is also called Friction Ridge Analysis. Fingerprints are used in investigative and legal settings

to establish the identity of victims and suspects, and to further establish their presence at a location or their contact with a particular object.

Fingerprints are often provided as the sole means of such identifications, a practice that is not as accurate as many believe.

As described in the NAS Report (Edwards and Gotsonis, 2009, pp. 5–7): Fingerprints, palm prints, and sole prints have been used to identify people for more than a century in the United States.

Collectively, the analysis of these prints is known as “friction ridge analysis,”which consists of experienced-based comparisons of the impressions left by the ridge structures of volar (hands and feet) surfaces.


Friction ridge analysis is an example of what the forensic science community uses as a method for assessing “individualization”—the conclusion that a piece of evidence (here, a pattern left by friction ridges) comes from a single unambiguous source.

Friction ridge analysis shares similarities with other experience-based methods of pattern recognition, such as those for footwear and tire impressions, toolmarks, and handwriting analysis.


Historically, friction ridge analysis has served as a valuable tool, both to identify the guilty and to exclude the innocent.

Because of the amount of detail available in friction ridges, it seems plausible that a careful comparison of two impressions can accurately discern whether or not they had a common source.


The first responders at a crime scene are usually police officers, fire department personnel or emergency medical personnel.

They are the only people who view the crime scene in its original cond

Their actions at the crime scene provide the basis for the successful or unsuccessful resolution of the investigations.

They must perform their duties and remember that they begin the process that links victims to suspects and to crime scene.


The first responders must always maintain an open and objective mind when approaching a crime scene and they should initiate crime scene security measures.


1. Assist the victim.2.Search for and arrest the suspect if still on

the scene.3.Detain all witnesses because they possess

valuable information about the crime scene. Keep witnesses separated to preserve their objectivity.


4.Protect the crime scene. Begin by using barrier tape, official vehicles, or other means to secure the scene. Establish a crime scene security log to record the names of all persons who enter or exit the crime scene. Do not smoke, drink, or eat within the secured crime scene and do not allow unnecessary persons or officials to enter or contaminate the scene.

5.Note and communicate to crime scene investigators all movements and any alterations made to the crime scene.


The only thing consistent about crime scenes is their inconsistency.

Because of their diversity, crime scenes can be classified in many ways.

1.Original or first criminal activity (Primary or Secondary)

2.Type of Crime (Rape Crime Scene, Murder Crime Scene)


4.Crime Scene Condition (Organized or Disorganized)

5. Location of the Crime Scene (Indoor or Outdoor)

6. Conduct/Type of Criminal Behaviour (Passive or Active)


Forensic Pathology Forensic pathology represents a

subspecialty within the medical specialty of pathology dealing specifically with the investigation of sudden, unexpected, and/or violent deaths.

The autopsy is central to the practice of forensic pathology.


Forensic Anthropology Forensic anthropology is a subspecialty

within the scientific field of physical anthropology.

Forensic anthropologists attempt to answer questions about bones, including questions regarding species of origin (human versus nonhuman), gender, age, race, stature, nutritional status, existence of disease processes, and the presence and character of skeletal trauma.


Forensic Anthropology (Continued) A forensic pathologist may consult with a

forensic anthropologist when attempting to address any of the questions above.

A frequent instance of consultation occurs when the forensic pathologist is presented with a badly decomposed or skeletonized corpse that is unidentified.


Forensic Odontology Forensic odontology is a subspecialty within

dentistry in which a dentist has specialized expertise in using dental examination to assist in the identification of human remains, and in the evaluation of bite-marks, wherein a bite-mark on a victim may be “matched” to a suspect .


Forensic Odontology (Continued) The majority of a forensic odontologist’s

involvement in forensic casework involves assisting forensic pathologists in the identification of bodies.

Assistance is usually provided in cases where the body is not visibly identifiable, and identification by fingerprint comparison or other means is not possible.

The most common types of cases are persons who are badly burned and those who are badly decomposed.


Forensic Entomology Forensic entomology is a subspecialty

within the biological science discipline of entomology (the study of insects) that primarily deals with insect succession patterns in decomposing human bodies.

Evaluation of insects (including larval stages, or maggots) found on decomposing bodies can permit scientific estimation of the time of death.


Forensic Entomology (Continued) In certain circumstances, information

regarding the location of death may also be ascertained.

Forensic pathologists do not consult with forensic entomologists in all decomposed cases, but will consult with them on select cases where estimating the time of death may be very important (for example, in homicides with decomposition and insect activity).


Forensic Toxicology Forensic toxicology is a discipline that

involves the identification and quantification of drugs and other poisons or toxins in body tissues, including blood.

“Screening tests” are said to be “qualitative,” where a test is either positive (indicating that the drug/toxin is present) or negative (indicating that the drug/toxin is not present).


Forensic Toxicology (Continued) When specific levels of drugs or toxins are

determined, the tests are said to be “quantitative.”

For a result to have forensic significance, two separate methodologies are required, an initial (screening) test, and a confirmatory (quantitative) test.

Another function of some toxicology laboratories is drug identification.


Forensic Toxicology (Continued) For example, if a bag of white powdery

substance is found in the pocket of a dead person, the substance can be submitted to the laboratory for identification.

Forensic pathologists rely a great deal on the forensic toxicology laboratory. In many jurisdictions, toxicology testing is performed on a majority of the autopsy cases.

In a significant percentage of forensic autopsy cases, the cause of death is related to the toxicology results.


There are two types of offenders:1. Organised Non-Social Offender 2. Non Organised Asocial Offender


He is highly intelligent He commits crime away from his area of

habitation He is neat He is highly organised He is cautious He leaves no evidence behind He leaves behind a perfect/organized crime

scene; arranged, tidy crime scene


He is of low intelligence He commits crime near his area of

habitation He is dirty and unkempt He is highly disorganised He is not cautious He leaves plenty of evidence behind He leaves behind a disorganized crime

scene i.e bloody, messy and strewn crime scene


mr. edwin osebe agasa. expert witnesses types of evidence forensic victimology ballistics dna...

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