Forensic Science

Do Now (pair share)

• Recall a famous crime scene, or a crime scene you have seen in one of the forensic TV shows.

• Question: What are some of the questions forensic scientists try to answer when analyzing a crime scene?

• 5 minutes to come up with a minimum of three questions. You may share your answers with your partner.

Some questions forensic scientists try to answer when analyzing a crime scene.

• 1. Who did it?2. What happened?3. When did it happen?4. How did it happen?5. Did it happen here or was another crime scene involved?6. Who is the victim?7. Why was this crime committed?8. What evidence is there to help prove the motive and the crime?

CRIME SCENE: Any physical location in which a crime has occurred or is suspected of having occurred.

ALIBI: Statement of where a suspect was at the time of a crime.

HOMICIDE: The deliberate and unlawful killing of one person by another; murder.

ACCOMPLICE: Person associated with someone suspected of committing a crime.

SUSPECT: Person thought to be capable of committing a crime.

Crime Scene Vocabulary

CRIME SCENE CLASSIFICATION1. Based on crime and victim’s location.

• PRIMARY CRIME SCENE: The original location of a crime or accident.

• SECONDARY CRIME SCENE: An alternate location where additional evidence may be found.

2. Based on size. Under this classification, a single macroscopic crime scene is composed of many microscopic crime scenes. For example, a gunshot victim’s body dumped in a field represents the following crime scenes: The body, the body’s wounds, the ground around the body. This microscopic classification is focused on the evidence.

3. Based on type of crime. Homicide, robbery, sexual assault, etc.

4. Based on condition. Organized, disorganized, mixed, which may offer clues as to the criminal behavior associated with the crime scene.

5. Based on physical location. Indoors, outdoors, car, etc.

Activity on Crime Scene

How would you classify the following two crime scenes?

• 1. In a jewelry store heist:• The thieves break into the store, take the

jewelry, get into their getaway car, and take the stolen goods to their apartment.

• 2. A man was strangled in his home. The perpetrators used the man’s van to transport the body and dump it into a nearby lake.

Answers• 1. Robbery (Indoors): The store is the primary

scene, whereas the thieves' getaway car and apartment are the secondary scenes.

• 2. Homicide: The home of the victim who was stabbed or shot by the offender is the primary crime scene (Indoors). The van and the point at the lake where the victim was dumped would be considered the secondary crime scenes (Outdoors).

How would you classify this crime scene?

Long Island Murders

• The remains of four victims were found in December 2010, while six more sets of remains were found in March and April 2011.[They are thought to be the work of the Long Island Serial Killer (also referred to by media sources as the "Gilgo Killer" and the "Craigslist Ripper"). This unidentified suspected serial killer is believed to have murdered at least four prostitutes since 2007 and dumped their bodies along the Ocean Parkway, near the remote beach towns of Gilgo Beach and Oak Beach in Suffolk County.

Classify these crime scenes. Why are they difficult to analyze?

Why is it important to ask questions?

• Students have used the QFT to develop science experiments, create their own research projects, begin research on a teacher-assigned topic, prepare to write an essay, analyze a word problem, think more deeply about a challenging reading assignment, prepare an interview, or simply get themselves “unstuck.”

How is evidence classified? 

 

•Do Now:

•Summarize Locard’s exchange principle. OR

•You are the first officer at a crime scene involving a victim. What is the first thing you must do and why?

• Evidence is classified into two main types:• Direct (testimonial): Includes first hand observations such as eyewitness accounts,

written statements, confessions, or video cameras. In court, direct evidence involves testimony of what witnesses saw, heard, or did.

Circumstantial (physical): indirect evidence that can be used to imply a fact but does not directly prove it. Only the suspect and the victim have direct knowledge of this evidence. It refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession.

Types of Evidence

Types of Evidence

Give some examples of circumstantial (physical) evidence which could be collected at a crime scene.

Answers

• gun, blood, hairs, fibers, soil, glass, tire marks, paint chips, explosives, fingerprints, tool marks, bullets, shell casings, pollen, spores, tire marks, leaves, DNA, etc.

• How could these types of evidence be classified further?

Circumstantial (physical) Evidence Classification

• Biological: Body fluids, hair, natural fibers, plant parts, DNA

• Physical: Bullets, casings, artificial fibers, tool marks, etc.

• Trace evidence refers to physical evidence that is found in small but measurable quantities.

THE JONBENET RAMSEY CASEThe 1996 homicide investigation of six-year-old JonBenet Ramsey provides valuable lessons in proper crime-scene investigation procedures. From this case, we learn how important it is to secure a crime scene. Key forensic evidence can be lost forever without a secure crime scene.

http://www.today.com/video/today/53372063#53372063

THE JONBENET RAMSEY CASEIn the Ramsey case, the police in Boulder, Colorado, allowed extensive contamination of the crime scene. Police first thought JonBenet had been kidnapped because of a ransom note found by her mother. For this reason, the police did not search the house until seven hours after the family called 911. The first-responding police officer was investigating the report of the kidnapping. The officer did not think to open the basement door, and so did not discover the murdered body of the girl. Believing the crime was a kidnapping, the police blocked off JonBenet’s bedroom with yellow and black crime-scene tape to preserve evidence her kidnapper may have left behind.

But they did not seal off the rest of the house, which was also part of the crime scene. Then the victim’s father, John Ramsey, discovered his daughter’s body in the basement of the home. He covered her body with a blanket and carried her to the living room. In doing so, he contaminated the crime scene and may have disturbed evidence. That evidence might have identified the killer.

THE JONBENET RAMSEY CASEOnce the body was found, family, friends, and police officers remained close by. The Ramseys and visitors were allowed to move freely around the house. One friend even helped clean the kitchen, wiping down the counters with a spray cleaner—possibly wiping away evidence. Many hours passed before police blocked off the basement room. A pathologist did not examine the body until more than 18 hours after the crime took place. Officers at this crime scene obviously made serious mistakes that may have resulted in the contamination or destruction of evidence. To this day, the crime remains unsolved.

Make a list of all mistakes

police made investigating

this crime scene.

How is evidence collected at a crime scene?

• DO NOW• Look at your examples of the circumstantial (physical) evidence

again:• Which of the examples narrows the ID to a single suspect?• Explain your answer.

Circumstantial Evidence Classification

• Circumstantial evidence can further be divided into:

• Class evidence: Narrows the identity to a small group of persons: Give examples

• Individual evidence: narrows the identity to one person. Give examples.

• Do Now:Which of the two is better evidence and why?

•  

AIM: How was class evidence individualized in the Wane Williams case?

1.Give 2 examples of class and 2 examples of individual evidence that can be found at a crime scene.

2.How can class evidence become individual evidence? Explain.

http://abcnews.go.com/Archives/video/wayne-williams-police-search-home-10136605

Wayne Williams

• He first became a suspect in the child murder case in May 1981. His car was spotted directly above the sound of a loud splash heard in the river by a stake out team. He was stopped by police and questioned, and claimed that he was going out of town to audition a young singer. This alibi fell apart after police found that the address and phone number he gave them didn't exist.

• Three days later, the nude body of 27 year-old Nathaniel Cater, who had been missing for days, turned up in the river. The medical examiner on the case ruled he had died of "probable" asphyxia.

• Hairs and fibers on one of the victims' bodies were found consistent with those from Williams' home, car, and dog. People working in Williams' studio also told police they had seen him with scratches on his face and arms around the time of the murders, which the police thought could have been inflicted by victims during a struggle.

Trial and conviction• Williams' trial began on January 6, 1982. During the two-month trial,

prosecutors matched 19 different sources of fibers from Williams' environment: his bedspread, bathroom, gloves, clothes, carpets, dog and an unusual tri-lobal carpet fiber to a number of victims.

• There was also eyewitness testimony placing Williams with different victims, blood stains from victims matching blood in Williams' car, and testimony that he was a pedophile attracted to young black boys. Williams himself took the stand, but alienated the jury by becoming angry and combative during a single instance.

• The jury deliberated for 10 hours before finding him guilty of murdering Cater and Payne. He was then sentenced to two consecutive terms of life imprisonment.

Controversy• Williams' conviction has been disputed. Many in the community did

not believe Williams, the son of two teachers, could have killed so many children and adults. On May 6, 2005, DeKalb County Police Chief Louis Graham ordered the reopening of the murder cases of four boys killed in the area between February and May 1981 that were attributed to Williams.

• However, the authorities in neighboring Fulton County, Georgia, where the majority of the murders occurred, have not moved to reopen the cases under their jurisdiction. Williams has always vehemently denied the charges. Dekalb County finally closed its case after finding no new evidence.

• On August 6, 2005, it was revealed that Charles T. Sanders, a white supremacist affiliated with the Ku Klux Klan who had been investigated for a role in the Atlanta child killings, once praised the crimes in secretly recorded conversations. Although Sanders did not claim responsibility for any of the deaths, Williams' lawyers believe the evidence will help their bid for a new trial.

What will evidence collected at a scene do for the investigation?

• May prove that a crime has been committed

• Establish key elements of a crime

• Link a suspect with a crime scene or a victim

• Establish the identity of a victim or suspect

• Corroborate verbal witness testimony

• Exonerate the innocent.

• Give detectives leads to work with in the case

Who is responsible for collecting evidence at the crime scene?Who else is allowed at the crime scene, and why?

POLICE OFFICERS are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime.

The CSI UNIT documents the crime scene in detail and collects any physical evidence.

The DISTRICT ATTORNEY is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge.

The MEDICAL EXAMINER (if a homicide) may or may not be present to determine a preliminary cause of death.

SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis.

DETECTIVES interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence.

Crime Scene Personnel

Step 1: InterviewThe first step in investigating a crime scene is to interview the first officer at the scene or the

victim to determine what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the investigators a place to start.

Step 2: ExamineThe second step in the investigation of a crime scene, which will help identify possible

evidence, identify the point of entry and point of exit, and outline the general layout of the crime scene.

Step 3: DocumentThe third step in the protocol involves creating a pictorial record of the scene as well as a

rough sketch to demonstrate the layout of the crime scene and to identify the exact position of the deceased victim or other evidence within the crime scene.

Step 4: ProcessThis is the last step in the protocol. The crime scene technician will process the crime scene

for evidence, both physical and testimonial evidence. It is the crime scene technicians responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory.

Crime Scene Protocol

Evidence Collection• Investigators should perform the evidence collection process in a systematic

and careful manner.

• The process begins with the preliminary crime scene survey/walk-through, followed by a determination of the evidence collection sequence to be used.

• The following equipment may be used in the evidence collection process:

• • Latex gloves/nitrile gloves (N-DEX, nonlatex).

• • Forceps.

• • Tweezers.

• • Scalpels.

• • Swabs.

• • Paper bags.

• • Plastic bags.

• • Cardboard boxes.

• • Wrapping paper.

• • Thermometer.

• • Plastic 5 gallon bucket with lid.

Best practice techniques for the collection of biological evidence include the following:

Dried Material Collection Technique

With gloved hands, slightly moisten the swab with distilled water. (The swab should be damp but not overly wet.)

Thoroughly rub the stained area using a single moistened swab for a small stain and multiple swabs for a large stain.

Air-dry the swabs.

Place each swab into separate package.

This package may be placed inside a paper envelope.

Collect a substrate/control sample from an unstained area using the same techniques.

• Liquid Material Collection Technique• A. When suspected biological evidence is found

on clothing or other absorbent surfaces, transport it to the laboratory in an appropriate container.

• Wet evidence should not be folded over on itself. Use paper wrapping to prevent contamination during the transfer.

• The item should be air-dried thoroughly in a drying locker and packaged in a container suitable for dried evidence.

• If the suspected biological evidence is in a liquid form on a fixed surface that cannot be transported (i.e., concrete floor), the substance should be recovered using the dried material collection technique:

Evidence Marking and Packaging• All evidence collected at a crime scene, or received at or during a crime

scene investigation, is inventoried and packaged prior to leaving the scene to prevent loss or cross-contamination

• Evidence which cannot be marked, such as soil, hair and stains, should be placed in an appropriate container or envelope. Always mark the outer packaging.

• When marking evidence directly, include the

• following:

• • Agency case number.

• • Item number.

• • Description of the item(s).

• • Date recovered or received.

• • Investigator’s initials.

• Evidence tape is used to seal the packaging and is marked with the investigator’s name or initials and the date sealed.

Establishing the Chain of Custody• The chain of custody documents the transfer of evidence/property from an

investigator to another

• individual, location or agency.

• The following information is included in the chain of custody:

• • List of evidence: the item number and a brief description.

• • All transfers must include the date and time of transfer.

• • The signature of the individual releasing the evidence to another individual or location.

• • The signature of the individual transporting the evidence.

• • The signature of the individual receiving the evidence from another individual or location.

• • Reason for the transfer as needed.

Errors in the Application of Forensic Science in the OJ Simpson Case

1. Nicole Brown Simpson’s body covered with blanket from inside her condo. This allowed for the possible transfer of trace evidence

from the blanket to the body and vice versa. 2. Crime scene photographs depict evidence in different locations. At the Bundy crime scene a bloody envelope is depicted in two different locations in the crime scene photographs. In the crime scene photos from O.J.’s Rockingham estate a pair of pants suspenders is depicted being in multiple locations in different crime scene photographs.

3. Blood missing from OJ’s reference sample tube?The nurse testified that he had drawn 8 ml of blood from OJ Simpson for reference sample. The amount was not recorded immediately as it should have been. Later on the LAPD crime lab indicated that the reference sample was only 6.5 ml of blood. The sample was not immediately placed into evidence as it should have been and the lead detective had it in his possession for several hours.

4. Blood “missed” on rear gate at Bundy drive.Majority of the blood samples were collected the day following the murders, June 13th 1994. However three blood stains on the back gate were not collected until three weeks later on July 3rd. The prosecution contended that these blood samples were missed during the initial crime scene investigation. The defense contended these blood stains had been planted there after the fact. They presented a photo taken the day after the murders in the area of the back gate where the largest blood stain was later found.

5. The Bloody Socks EvidenceSocks found at the crime scene at O.J. Simpsons Rockingham Estate were collected as evidence in the investigation. Initially, no blood was reported to be on the socks. Months later, a blood stain roughly the size of a quarter was reported to be on the socks. The blood stain was on both sides of the sock. This would not be possible if someone was wearing the sock at the time they committed the crime because their foot would block the blood from reaching the other side, therefore making a wet transfer of blood impossible at the time.

6. Improper handling of forensic evidence

An LAPD investigator admitted that he spilled some of O.J. Simpsons blood from a reference tube and then shortly after this he handled evidence such as the bloody glove. This could have caused the transfer of Simpson’s blood to these pieces of evidence.

7. DNA testing in the caseThe DNA which was contaminated multiple times due to the sloppy procedures. The blood reference samples from Nicole Brown-Simpson and Ronald Goldman were contaminated with O.J. Simpsons DNA. DNA from the drops of blood at the Bundy Crime scene was degraded because it was left in hot moist conditions (on wet cotton swatches in plastic bags in a truck on with warm temperatures for several hours).

8. The Bronco Crime SceneThe biggest error attributed to the Ford Bronco is that it was not kept secure during the investigation. At least two unauthorized people entered it when it was in the police’s possession, possibly looking for souvenirs, possibly planting evidence, at the very least disrupting the integrity of the Bronco as a crime scene.

Exit Slip: What evidence would you collect why and

how?

Drug Chemistry – Determines the presence of controlled substances and the identification of marijuana

Trace Chemistry - Identification and comparison of materials from fires, explosions, paints, and glass.

Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers, woods, soils, building materials, insulation and other materials.

Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva.

Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons.

Latent Prints - Identification and comparison of fingerprints or other hidden impressions from sources like feet, shoes, ears, lips or the tread on vehicle tires.

Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired bullets, cartridges, guns, and gunpowder patterns on people and objects.

Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such as a hammer used to break a door or a screwdriver used to pick a lock.

Questioned Documents - Examination of documents to compare handwriting, ink, paper, writing instruments, printers, and other characteristics that would help to identify its origin.

Investigating the Evidence

Source: http://www.isp.state.il.us/forensics/

Forensic Science disciplines at the Illinois State Police Crime Labs