What is Forensic Science?
The science involved in solving a crime
What are the different types of scientists involved in forensic science?
Actually there are many, here are a few.
* Forensic Pathologists deal with tissue and dead bodies
*Forensic Anthropologists deal with bones
Ballistics experts deal with guns and ammo
Part II:
Three Types of Evidence
1.Personal (Testimonial) Evidence
Testimony from a person at the crime scene. ♦ Can be subjective and colored by a person’s attitude. ♦ Ex. – Eyewitness, confession, hearsay (not usable in court).
2.Physical Evidence
Something at the scene of the crime that links the perpetrator to the crime. ♦ Objective and remains the same for each observer. ♦ Ex. – Fingerprints, Fibers, Hair, Glass, Footprints, etc.
3. Miscellaneous Evidence
Does not fall into the two previous groups. ♦ Can be subjective or objective and not always admissible in court. ♦ Ex. – Polygraph (not admissible), voice analysis (depends), psychological exams (admissible), circumstantial evidence (crime happened on a boat, suspect loves boats).
1. Personal Evidence in detail
List of Pros of Personal Testimony
1. Eyewitness testimony can influence jury decision.
A jury’s role in a court hearing is to identify credibility issues and assess the truth of the witness’ statement. So by having credible witnesses under oath, the jury will be able to determine whether the defendant is guilty of the crime he or she is being accused of.
2. Eyewitness testimony can shed light into the sequence of the events that took place while the crime was committed.
This helps the jury and the lawyers better understand everything about the case as the eyewitness testimony explains how the crime was committed, who was involved and where it happened. As a result, a motive could be established based on the witness’ account of the story. Consequently, it will help the judge come up with the best decision in the end.
3. Eyewitness testimony can be used as evidence in court.
A witness’ report of what took place on that fateful day can prove that the crime was really committed. It can be used to determine how, when and where the felony was committed. Most importantly, it can provide support of the criminal case filed in court, i.e., identifying the weapon used, offering additional information that will help the court identify the perpetrator, etc., persuading the judge and jurors to convict the suspect.
4. Eyewitness testimony is generally reliable.
When the testimony is obtained and reported right after the event took place, the witness’ memory is still fresh, which means that there is a higher chance that his or her account of the incident is still vivid in his or her mind. This makes his or her testimony more reliable. When this is presented to the authorities and in court, the judge and the investigators will be able to better understand and envision exactly what occurred. As a result, they will be able to determine the best course of action to take.
List of Cons of Personal Testimony
1. Eyewitness testimony may not always be accurate.
Several studies have been conducted in the past on human memory and on people’s capacity to remember events and details, some of which were erroneously recorded and stored in their minds. In the mid-70s, Elizabeth Loftus did experiments that showed the effects of introducing false facts into a person’s memory by a third-party. The results reveal that some of the subjects false remembered seeing images that were not there during a particular incident. The experiments also involved injecting words in certain questions that lead the subjects to incorrectly provide accounts of what they saw. All of this show that sometimes eyewitness testimonies may not be accurate.
2. Eyewitness testimony rely only on people’s memory.
The problem with this is that human memory has the vulnerability to be bias, especially when a third-party uses trigger statements that could cloud a witness’ better judgment and most importantly, memory of what really happened. Aside from that, it has been proven that retelling a story in a neutral fashion is rarely done, affecting one’s memory. Oftentimes, stories are retold in a way that is tailored to the listener, distorting the memory.
3. Eyewitness testimony can have parts that are made up by the witness due to nervousness or fear.
Pressure can also affect a person’s memory. Some people feel pressured when they everyone else in the room is counting on them. This might lead them into saying something that is wrong or inaccurate. Oftentimes, emotions get the best of us. When that happens, people might remember things or events differently. They might not be able to accurately recall the sequence of events or crucial details that will help solve the case.
4. Eyewitness testimony can convict the wrong person.
Leading questions can make a witness or a victim “recall” things, events or persons that never occurred. Because a jury puts great emphasis and value on a witness’ memory of the incident, despite the lack of physical evidence, the testimony can put the wrong person behind bars. Even if the falsely convicted felon may be freed from jail, the decision of the court will forever change his or her life. He or she could lose his dignity, job or even his or her love ones.
1. Eyewitness testimony can influence jury decision.
A jury’s role in a court hearing is to identify credibility issues and assess the truth of the witness’ statement. So by having credible witnesses under oath, the jury will be able to determine whether the defendant is guilty of the crime he or she is being accused of.
2. Eyewitness testimony can shed light into the sequence of the events that took place while the crime was committed.
This helps the jury and the lawyers better understand everything about the case as the eyewitness testimony explains how the crime was committed, who was involved and where it happened. As a result, a motive could be established based on the witness’ account of the story. Consequently, it will help the judge come up with the best decision in the end.
3. Eyewitness testimony can be used as evidence in court.
A witness’ report of what took place on that fateful day can prove that the crime was really committed. It can be used to determine how, when and where the felony was committed. Most importantly, it can provide support of the criminal case filed in court, i.e., identifying the weapon used, offering additional information that will help the court identify the perpetrator, etc., persuading the judge and jurors to convict the suspect.
4. Eyewitness testimony is generally reliable.
When the testimony is obtained and reported right after the event took place, the witness’ memory is still fresh, which means that there is a higher chance that his or her account of the incident is still vivid in his or her mind. This makes his or her testimony more reliable. When this is presented to the authorities and in court, the judge and the investigators will be able to better understand and envision exactly what occurred. As a result, they will be able to determine the best course of action to take.
List of Cons of Personal Testimony
1. Eyewitness testimony may not always be accurate.
Several studies have been conducted in the past on human memory and on people’s capacity to remember events and details, some of which were erroneously recorded and stored in their minds. In the mid-70s, Elizabeth Loftus did experiments that showed the effects of introducing false facts into a person’s memory by a third-party. The results reveal that some of the subjects false remembered seeing images that were not there during a particular incident. The experiments also involved injecting words in certain questions that lead the subjects to incorrectly provide accounts of what they saw. All of this show that sometimes eyewitness testimonies may not be accurate.
2. Eyewitness testimony rely only on people’s memory.
The problem with this is that human memory has the vulnerability to be bias, especially when a third-party uses trigger statements that could cloud a witness’ better judgment and most importantly, memory of what really happened. Aside from that, it has been proven that retelling a story in a neutral fashion is rarely done, affecting one’s memory. Oftentimes, stories are retold in a way that is tailored to the listener, distorting the memory.
3. Eyewitness testimony can have parts that are made up by the witness due to nervousness or fear.
Pressure can also affect a person’s memory. Some people feel pressured when they everyone else in the room is counting on them. This might lead them into saying something that is wrong or inaccurate. Oftentimes, emotions get the best of us. When that happens, people might remember things or events differently. They might not be able to accurately recall the sequence of events or crucial details that will help solve the case.
4. Eyewitness testimony can convict the wrong person.
Leading questions can make a witness or a victim “recall” things, events or persons that never occurred. Because a jury puts great emphasis and value on a witness’ memory of the incident, despite the lack of physical evidence, the testimony can put the wrong person behind bars. Even if the falsely convicted felon may be freed from jail, the decision of the court will forever change his or her life. He or she could lose his dignity, job or even his or her love ones.
2. Physical Evidence in detail
Types of Physical Evidence
- biological evidence (e.g., blood, body fluids, hair and other tissues)
- latent print evidence (e.g., fingerprints, palm prints, foot prints)
- footwear and tire track evidence
- trace evidence (e.g., fibers, soil, vegetation, glass fragments)
- digital evidence (e.g., cell phone records, Internet logs, email messages)
- tool and tool mark evidence
- drug evidence
- firearm evidence
Class vs Individual Physical Evidence
The best evidence is the type that can be individualized to a single, specific source, so that there is no doubt as to what the source of the evidence is. This type of evidence can place a suspect at a crime scene, associate a suspect with a victim, and sometimes even prove who committed a crime. Human characteristics that can be linked to or individualized to a particular person are fingerprints, DNA, handwriting, and voiceprints. The forensic scientist is always trying to individualize evidence so that it will have more value in the case. If this is not possible, the evidence may be found to be consistent with a particular source. This is called class evidence. Class evidence alone may not be very convincing in a crime, but if there are many different types or pieces of class evidence, the value can be considerable. Examples of class evidence are hair, fibers, soil, and glass fragments.
3. Miscellaneous Evidence in detail
Polygraph Machine: The "Lie" detector test
* NOT admitted in court
* Used in investigation by the police (It is surprisingly accurate!)
* NOT admitted in court
* Used in investigation by the police (It is surprisingly accurate!)
Psychological Tests ARE admitted.
Information from an interrogation
Part III:
CRIME SCENES
Locard's Principle:
Something from the crime scene is always left with the perpetrator and something of the perpetrator is always left at the crime scene.
Procedure at a crime scene:
First Responding officers priorities:
1. Assit anyone injured
2. Arrest any perpetrators/suspects
3. Secure the area
4. Begin taking notes and photographs
5. Collect evidence with great care
6. Interviewing witnesses or suspects