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Forensics Methods of Identification Why is forensics important? What is Forensic Science? Forensic science is the application of scientific techniques to investigate a crime. Forensic scientists collect and analyze evidence from a crime scene. Police use this evidence to find out what happened and who was responsible. The evidence can also be used in the legal system to convict someone of a crime. What kind of questions can Forensic Science help us Answer? (Student Brainstorm). Forensic Scientists Forensic scientists will help to collect scientific evidence at a crime scene. They can be specialists in a variety of fields: Psychology Dentistry Anthropology Medicine IT However regular police can also collect evidence at a crime scene if they have been specially trained. Forensic methods of identification It can often be difficult to determine the remains of a dead person, especially if all that remains are bones However without proper identification it can be difficult to determine the identity of the living as well. In the past criminals could just change their name and move to a new location. What are some forms of identification we use today? (Quick Student Discussion) Today we have various methods for identifying remains and establishing the identity of perpetrators The Bertillon system In 1870 the Chief of Criminal identification in Paris, Alpharose Bertillion designed a method for an identification system. His system involved measuring and recording the dimensions of bony body parts This was called anthropometry The assumption was that no two peoples measurements were exactly the same Disadvantage: This method eventually was retired in 1905 because a man was wrongly convicted and sent to jail for a crime his twin brother committed! Photographic Identification In 1854 photography was invented In the 1870‟s it was generally used with anthropometry for identification By the 1900‟s it was widely used by itself as a form of identification Still widely used on various forms of identification e.g. Drivers licenses Disadvantage: Has limitations if used as the sole means of identification Positive identification by a witness looking at an album of photos is difficult. Tony Mokbel Identikit and Composite Drawings Before photographs drawings of wanted criminals were commonly used e.g. Wanted Posters Another System called Identikit gained popularity in 1960‟s because it uses pre-drawn facial features that can be slotted together without the need of an artist. More recently computerized methods can be used to create a drawing of a suspect in minutes. Disadvantage: It is often difficult for a witness to get all features correct Only 2% of composition drawings ever led to a positive identification Activity : Identikit Challenge The Program will flash a face up for 10 seconds You then have to reconstruct that face by selecting individual features http://asistm.duit.uwa.edu.au/forensics/faces/ Biometric Facial Recognition Specialized computer systems and software can quickly and accurately identity a person from a single stored image in a database. Facial recognition measures the points between different facial features (eg Eyes, nose, ears and chin) and compares this to the files on a database What are some types of evidence? Fingerprints Fingerprints are found on the palms of hands and soles of feet of all primates They allow us to grip things Each fingerprint consists of ridges and valleys These will grow back in the exact some pattern Fingerprinting Cont. Fingerprints are compared in the following manner: The same minutiae are present The minutiae flow in the same direction The minutiae occupy the same relative positions to each other Activity: Super Prints! Make a small bowl from the aluminum foil and place into a container Place a small cup of hot water in the container Press you finger onto a microscope slide Add 10 to 15 drops of superglue into the bowl Place the slide into the container and seal lid Focus a light or heat lamp on the container Once the finger print has formed see if you can identify some of the minutiae that are present Project: Design your own crime science The major piece of assessment for this unit will be a self designed crime. In your self designed crime you must include a number of different pieces of forensic evidence that will conclusive indicate a specific suspect. These may be things like: Finger prints DNA tests Handwriting analysis Video surveillance We will cover a number of these topics and more over the course of this subject At the end of each week you must hand in the work you have done on the project: In the first week this may be general brainstorming or the formation of a story narrative for your crime. I will provide you with feedback on what you have submitted The final three lessons of this unit will be as follows: Finalization of project work (Single lesson) Presentation and assessment of work by peers (Double lesson) Additional Resources List of forensic terminology: http://suicideandmentalhealthassociatio ninternational.org/forensicsgloss2.html Forensics From the eye to DNA Iris and Retina Identification A persons identity can also be identified using a biometric device, like a retina scanner. These scanners will either examine the iris pattern or the blood vessels in the eye These type of scanners are more accurate because: Two scans are taken (one for each eye) Cannot be forged with a glass eye There are 266 identifiable features in the iris (this makes it far more accurate than a fingerprint) Iris does not change over time Forensic Odontology and anthropology Odontology is the scientific study of teeth. Odontology is often used by forensic scientists to identify a victim by his or her teeth Forensic anthropology is the application of the science to study the remains of a human skeleton Identifying a „known‟ body If there is sufficient evidence to assume the identity of a body (e.g. recovered from a house fire), x-rays of the body may be performed. X-rays will show if any previous bone breaks have occurred or whether pins for serious breaks are present. These are then compared to hospital records for the suspected victim Additionally X-rays of the teeth are taken to compare to dental records as well Identifying an “Unknown” body It can sometimes be difficult to identify a corpse, especially if it is only a skeleton or individual bones. However a forensic anthropologist can gather information about the body from careful examination of the bones. For example: Femur (main bone of the leg) can be measured to determine the height of a person. Whereas sex and age can be determined from examination of the pelvis and skull. Activity: Inferring height form bone length Femur Humerus In this activity you will measure various class members femurs From this data we can try to infer the height of people in the class. We will then check our results for accuracy! Check handout for more information DNA Profiling DNA or Deoxyribonucleic acid is a very important molecule found in all living cells. Its structure carries genetic information or a blueprint for an entire organism. We get half of our DNA from both parents and as a consequence DNA is unique to an individual, except identical twins. DNA fingerprinting or profiling was first used as technique in 1985 and was initially used to identify genetic diseases. It was used soon after in forensic science and criminal investigations DNA – Deoxyribonucleic acid The process begins with a blood or cell sample from which DNA is extracted. The DNA is cut into fragments The fragments are then separated by size via electrophoresis on an agarose gel. The DNA band pattern can then be transferred to a nylon membrane or a photograph can be taken. The band pattern formed is unique to every individual (except twins) Activity: Who‟s the father? On left we can see two examples of DNA fingerprints one is simplified and the other complex. On your handout are somewhat simplified DNA profiles for a child, its mother and two possible fathers. Your job is to work out who is the father by comparing the DNA bands! Remember bands present in the child have to come from either its mother or father. Forensics Is it real? How do you Prove a Document is real? Analysis of Handwriting When we analysis handwriting we are trying to prove the identity of the writer. This could be from a Ransom note or simply a signature on a check. Activity: Handwritten forgery! On a piece of paper sign your name twice. Circle one of the signatures (this will be the reference sample) Now swap the piece of paper and pen with a partner Your partner will now attempt to copy your signature Pass the piece of paper to a third person and see if they can spot which signature is the forgery! Printer Matching Print outs from a specific computer can be matched by how the printer leaves marks on the paper as the paper passes through the printer This can be seen at low light and photographed. Additionally the ink from the printer can also be matched. Ink Analysis Each brand of ink has its own “chemical signature”. Slight variations in the chemical make-up of different brands of ink cause it to leave a different pattern when dissolved Slight variations in the chemical make-up of different brands of ink cause it to leave a different pattern when dissolved Activity: Ink Analysis Draw a single dot or a line on a strip of chromatography paper. Approximately 4 cm from the bottom of the paper. Fill a small beaker with ethanol so the liquid is only 1 to 2 cm high. Place your strip of paper into the beaker so that only 1 to 2 cm is submerged and that your dot or line is only a few cm away from the ethanol. Ink Analysis Problems associated with the method used in class: Destructive test (can‟t do it if evidence must be preserved) Difficult to differentiate between inks with a very similar signature with the naked eye. “Crude” method of identification. Other non-destructive methods of forensic ink analysis: Infrared luminescence/reflectance (where infrared is used to identify chemical signatures. Capillary electrophoresis (where a tiny amount (nanoliters) of the ink is injected into a silica capillary filled with a buffer solution, then an electrical current is passed through it. Databases for these two methods are currently being compiled. Forgery Many criminals attempt to forge many types of currency or other documents Therefore the government and banks have developed technologies to make it more difficult to make successful forgeries. Upon closer examination of forged bills some common mistakes are: Identical serial numbers Poor printing paper Differences in printer inks Lack of UV markers How could we make documents harder to Forge? Anti-Forgery technologies Forensics: Collecting Evidence What is evidence? Wherever you go and whatever you do you leave behind proof that you were there. In a criminal investigation this is called evidence. Evidence can come in various forms. Can you think of different types of evidence you might find at a crime scene? Types of evidence Evidence could be: Eyewitness – they can give written or verbal accounts. Physical evidence: Fingerprints Shoe prints Hair or fibers Blood Digital evidence Collecting Fingerprints A common for of evidence is the finger print. Fingerprints are formed from contact with non-porous surfaces: Glass Plastic Mirrors / Windows Steering wheels Light colored surfaces are „dusted‟ with a black carbon powder, while white aluminum powder is used for dark surfaces. Porous surface fingerprints Fingerprints can be picked up on porous surfaces such as: Stone Raw or unpolished wood Technique involves using high powered „Poly lights‟ that cause fingerprints to fluoresce Collecting Body Products and Fibres Whether a fibre is synthetic or derived from an organism it can be examined under a comparison microscope. However finding a match from one fibre at a crime scene and one from a suspect is strong circumstantial evidence but not conclusive What are some other biological forms of evidence? Collecting Impressions –Tool Marks Most crimes are committed using a variety of tools such as: and Knives Pistols Crow Bars and Wire cutters Screw Drivers and Hammers When criminals use these tools to commit a crime they can leave behind marks or damage to material or persons they come into contact with. Tool Marks The marks made are generally lines (called Striations) are caused because of imperfections on the surface of the tool. Tools used on human tissues do not generally leave marks or striations. However wounds found on a victim can generally indicate, the size, shape and length of a weapon. Track Impressions Impressions can be left behind from our feet, shoes or even the tyres of our cars. How might tracks be left behind? Despite that shoes and tyres are mass produced to be identical there are still slight Imperfections that can tell individual tracks apart. Activity: Tyre Prints Paint a small section of each tyre with black paint Place paper on the section that has been painted Peel the paper off and wait for it to dry. While it is drying collect other tyre samples Now swap your images with another group. Can you match the impressions to particular tyres? What are some factors you have to consider when collecting evidence? Forensics: Biological and Technological Evidence Collecting biological Evidence Biological evidence can include the following: Seeds Blood DNA from bodily secretions Microscopic pollen Can you think of any other forms of biological evidence? Other Biological evidence Water organisms In cases of drowning, water based organisms like Diatoms. Diatoms are partly made of a substance called silica, which can from long lasting shapes even after death. Different bodies of water will have different colonies and populations of diatoms and this can be used to pinpoint the location of where the drowning occurred. Other Biological evidence Insects Insects can be important in determining both the location and the time of death . Time can be determined because insects have very specific life cycles throughout the year. Whereas the location will depend on the are or ecosystem the insect is derived from. Activity: Time of Death Worksheet The forensic – Time of Death worksheet will be began in class It includes information about life-cycles of various insects Use this information to determine the time of death in different cases Whatever you don‟t complete in class do as homework! Collecting electronic evidence Electronic evidence can consist of: Photographs Video footage Computer and internet records Phone Records Can you think of any other forms of electronic evidence? Video Imaging CCTV (Closed circuit television) are routinely used in criminal investigations to: Establish the time a crime was committed To identify perpetrators Footage can be paused and investigators can use computer software to enhance images for crucial details Mobile Tracking! When you mobile phone is switched on it can be used to locate you! Mobiles can be tacked down to approximately a 100 metre radius Criminals however might use this as an alibi or could plant someone else phone at the scene of a crime! Data Recovery Everything you do on your computer is recorded When you format or delete something it still exists on your hard drive as machine code (1‟s and 0‟S) What you erase is the way the computer accesses the machine code Investigators can use special data recovery programs to restore data from a computer Activity: Image Enhancement We will take a number of photos in class of: Car number plates Or students from a distance Street Signs These images will be taken at a distance so the object of the photo is somewhat unclear We will then use various image programs on a computer to attempt to enhance the image Forensics: Who, what and why? Who saw it? Eyewitness accounts can be integral part of establishing how or why a crime occurred This is especially true if witnesses are familiar with the victim or the offender Sometimes eyewitness account provide crucial details about a crime like: License plate details Identifying details about an offender Arguments or sounds they might have heard Police always try to get eyewitness accounts as soon as possible, because as time goes on the reliability of a witnesses memory deteriorates. What they do by habit A criminal habit is called a modus operandi or „MO‟. It refers to a preferred method of committing a crime This becomes more apparent over time as a criminals skills improve Activity: Habits Write down your daily habits: Consider in what order you do things from the moment you get up to when you get to school Do you do similar things every morning? Are there things you do only on some mornings? Modus operandi Some examples of „MO‟ are: Murder: serial murders usually have a defined technique for committing a murder and getting rid of the remains Time and date: Some criminals may commit crimes during certain times. Could indicate whether they are unemployed, single or work during the day. Location of similar offenses: Repeat criminals often commit crimes in areas they are familiar with. What are some other types of MO’s you can think of? Who might they be? Criminal profilers can use the information gained from a crime scene and the MO to establish a psychological profile of an offender. Profilers may also use information about the location of crimes to narrow down where a new crime is likely to occur However criminal profilers can sometimes be a hindrance to an investigation because police can overlook a suspect because they do not fit a certain profile What does a bloody mess tell us? In a violent crime such as a murder there is usually a lot of blood present at the scene. Blood patterns can : Indicate a weapons striking movement Indicate the movement of a victim and an offender Blood stains fade with time – therefore can indicate the time a crime occurred What information could wounds on a body indicate to us? Wounds on the body Wounds on the body can indicate: Whether a blunt or sharp object was used on the victim Wounds found on the right side of a victim may indicate the offender was left handed. Pieces of a weapon or fibres from the offender may be caught in the wound. What do gunshot injuries tell is? The height and direction of bullets can be determined by drawing a line from the wound in a victim or from a bullet lodged in a wall In an autopsy a entry wound will be small while a exit wound will be large. During an autopsy a bullet may be recovered which can later be matched to an offenders weapon. Why did a car crash occur? Three factors to consider in a car crash: The vehicles involved The environmental conditions The condition of the drivers The biggest factor in a crash is usually driver error Skids marks on the road can indicate how a crash occurred and the speed that vehicles were traveling at. Activity: Piecing it together! http://www.discoverychannel.co.uk/crime/csi/ Forensics: Crime scene thinking and investigation Crime Scene Thinking Ongoing Assessment Amy La Tour‟s body was found in her bedroom last night, as shown, with her pet canary strangled in its cage. Henry Willy and Joe Wonty, her boyfriends; Louis Spanker, a burglar known to have been in the vicinity; and Celeste, her maid, were questioned by the police. Can you solve the case? Dropout Ongoing Assessment As the clock struck five, ninety- year old Mrs. Mirabel Fallwell dropped out of the window of her spacious twelfth-floor apartment. On the fourth stroke she struck. Detective Amos Shrewd investigated shortly afterwards and found the room as you see it. Jerry Jarvis, Mrs. Fallwell‟s nephew and heir, said that the portrait on the wall of his beloved aunt was one he himself had painted. Under questioning, he claimed that he had been at the far end of the apartment at the time of the tragedy and that he knew nothing about it until informed by the police. Would you charge Jarvis with homicide and why? Dropout - Hints Ongoing Assessment Is there a reason why Mirabel interrupted her phone call and went to the window? Did Mirabel rush to the window? Is it likely that she brought a footstool to the window? Is it reasonable to suppose that Mirabel had a dizzy spell at the window? Did she try to keep herself from falling out of the window? Do you think she committed suicide? Crime Scene Investigation “When you have eliminated the impossible, whatever remains, however improbable, must be the truth” - Sherlock Holmes Scenario Dr. Wilson Sherwood was working late in his office keen to avoid the two women in his life; Annette Jennings and Cara Banner. Both had recently found out that he was dating them at the same time. Both were not exactly happy with him. The following morning (5/8/07) Janice Hurley – a co worker of Dr. Sherwood – discovered his body, a suicide note and a bottle of morphine pills. Was it suicide or something more? Evidence Performance for Understanding Solving the Mystery Each group has the same case file Within the Group you will discuss and solve the case Each group must present their case to the class with justifications based on any evidence they have.
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