Forensic Science: A Brief Introduction to the Disciplines

Transcription

1 Forensic Science: A Brief Introduction to the Disciplines November 2015 Jane Austin (Any errors in this presentation are all mine)

2 Today s Session Historical Context Overview of Forensic Science Disciplines How they are used in crime investigations

3 Historical Context Forensic Science dates back to 12thC gathered momentum in 17thC The word forensiccomes from the Latin, forēnsis, meaning "of or before the forum." Term originates from Roman times (a criminal charge was presented to a group of public individuals in the forum). Autopsy-from Greek, from autoptēs eyewitness, from autos self + optos seen to see for oneself Recently, made popular in books and Tv series such as CSI, NCIS, Silent Witness

4 UK Sir Bernard Spilsbury Studied at St Mary s Hospital, Paddington in Specialised in emerging science of FORENSIC PATHOLOGY First and most famous case was the trial of Hawley Harvey Crippen ( Dr Crippen )

5 Dr Crippen Provided forensic evidence that the victim found in Crippen's house was Mrs Cora Crippen Based on a scar on a small piece of skin from the remains. But.

6 Spilsbury s Cases Spilbury'sauthoritarian approach and his unnerving self-belief gave rise to criticism among judiciary Recent research has shown that some of his conclusions led to miscarriages of justice That said, in 2008, files containing Spilsbury s detailed notes on deaths (from ) went to Sotheby's and were acquired by the Wellcome Library, London.

7 Wellcome Trust Biomedical research charity, established 1936, to fund biomedical research, support public understanding of science, and improve human and animal health. UK s largest provider of non-governmental funding for scientific research and one of the largest providers in the world. In medical research, it is world's secondlargest private funder after Bill & Melinda Gates Foundation (ref. FT)

8 Wellcome Trust Well worth a visit!

9 USA - Frances Glessner Lee ( ) In 1936 inherited the family fortune. Developed a passion for forensics, inspired by her brother s friend, Magrath, who was Boston s medical examiner Wanted to reform the country s legal medicine system. Donated money to Harvard to create a Chair for Legal Medicine and GB Magrath Library of Legal Medicine Established the first US forensic pathology program Most remembered for her dioramasof crime scenes The Nutshell Studies of Unexplained Death"

10 Dioramas of Crime Scenes

11 Dioramas of Crime Scenes

12 Forensic Disciplines Biology, Chemistry, Physics Anthropology Botany and Ecology Blood Pattern Analysis Dentistry Digital DNA Profiling Engineering Entomology Pathology Psychology And many more..

13 Forensic Botany

14 Forensic Botany Scientific study of plants, or the application of plant sciences to criminal investigations. Incorporates a number of sub-disciplines: palynology (pollens) dendrochronology(tree rings) limnology(aquatic environments) systematics(the classification of plants) ecology(ecosystems), and molecular biology.

15 Forensic Botany Forensic botanists examine plant matter to determine their species and origin. Suspects may leave behind plant parts, spores or seedsadhered to their clothing. Some species found only in limited areas. their presence at the crime scene may indicate where suspects have been or where they live/work. Forensic botanists also can be essential in locating clandestine gardens or greenhouses used to cultivate such illegal plants as marijuana.

16 Pollen Powder-like, abundant and easily transported. Pollen grains are often found on clothes, hair or skin. Can connect a suspect to a victim or crime scene. Images: Rob Kesseler Madeline Harley If investigators find a rare plant type near a murder victim, the presence of its pollen on suspect could place them at the scene.

17 Pollen Even for common plants, each environment has its own unique combination of pollens; this 'signature' can link an individual or object to a location. Images: Rob Kesseler Madeline Harley Pollen signatures may also indicate that a body has been movedor suggest the type of area where the original crime took place.

18 Botany and hidden graves When soil disturbed, certain plants quickly invade the fresh surface. Other species follow in successionuntil the area recovers. But the new composition and distribution is never identical to original plant community. Also, a buried body may chemically change the soil, and may promote or inhibit growth-area will be different from its surroundings. These differences may be visible for decades.

19 Botany and the time since death Diatoms can be used to diagnose death by drowning in freshwater. Botanists identify number and species of diatomspresent in lungs and other tissues, correlate them with flora from location of body. Diatoms vary seasonally, and this can also help in approximating time since death. Unique Signature' of an aquatic habitat can match a body to a given location

20 Botany and time since death Trees and roots are also useful for determining elapsed time since death Woody plants and trees grow in annual cycles and the growth rings can provide clues to the timing of an event, sometimes centuries later. Particularly accurate if roots grow through clothing or bone. Even partial damage to root growth can suggest the period since the burial occurred.

21 Forensic Dentistry

22 Forensic Dentistry Main areas of practice: Identification of human remains Identification in mass fatalities Assessment of bite mark injuries Assessment of cases of abuse (such as child, spouse or abuse of the elderly) Age estimation, race, occupation, socioeconomic status

23 Blood Pattern Analysis (BPA)

24 Blood Pattern Analysis The interpretation of bloodstains at a crime scene in order to recreate the actions that caused the bloodshed. Analyse size, shape, distribution and location of bloodstains Form opinions about what did or did not happen.

25 Typical scene

26 Blood Pattern Analysis Chemical considerations-red to brown as oxy-haemoglobin changes to methaemaglobin and haemichrome Physical considerations -fluid to solid, effects of gravity, viscosity, surface tension Flight characteristics -angle of impact, area of origin

27 Bloodstain Pattern Analysis

28 Digital Forensics

29 Digital Forensics Digital Forensics is study of information stored or transmitted in digital form that may be used in trial Before accepting digital evidence, a court determines if evidence is relevant, authenticand whether copy or original is acceptable. Need assurances regarding chain of custody

30 Digital Evidence Use of digital evidence increased in last few decades. Many high profile cases in the press Courts have allowed the use of range of evidence: s, digital photos, video and audio files Instant messaging histories ATM transaction Logs Accounting programs and spreadsheets WP documents Internet Histories, Database records Contents of computer memories GPS tracking/mobile Records Logs for hotel electronic door locks

31 Defending a Digital Case Common lines of defence are that: Trojan or 'pop-up' was responsible for presence of any illegal material on the defendant's computer. Such material was unsolicited and was 'pushed' to them via MSN, a peer to peer application such as Kazaa or . It was one-time idle curiosity.

32 Prosecuting a Digital Case Such explanations can be countered by proving that the defendant had sought such material by: signing up to a service using a credit card searching within a peer-to-peer application entering keywords in an internet search engine sheerquantities of material and periods of exposure For digital evidence to be admissible, a clear chain of custody required, detailing who had access to digital device & when, contemporaneous notes of all actions taken, particularly in relation to the technical processes.

33 DNA Profiling

34 DNA Profiling Developed from two independent breakthroughs in molecular biology: In USA, the polymerase chain reaction (PCR) was invented by Kary Mullis In UK, DNA fingerprinting was being discovered by Professor Sir Alec Jeffreys at the University of Leicester. Multi-locus probing (MLP) technique results in probes binding to multiple DNA fragments, giving rise to traditional 'bar-code' pattern.

35 DNA Short Tandem Repeats DNA profiling involves the testing of highly variable regions of a person s DNA that contain short repeating sequences called STRs (short tandem repeats). Because we inherit DNA from both parents, DNA profiles can be used to confirm if people are closely related eg paternity, siblings STR very sensitive technique, requires only a small quantity of DNA eg blood, semen, skin, saliva, mucus, perspiration and the roots of hair

36 First Conviction using DNA Profiling Professor Jeffreysused DNA techniques to link semen stain samples, collected from two rapes/murders that occurred 3yrs apart (1983 & 1986), in a small Leicestershire village. Semen was type found in only 10% of men, and was from someone with Type A blood group. As a result, first mass DNA profile screening in the world was undertaken in Leicester Blood and saliva samples from 4,000 men with no alibi who lived in the local villages

37 First Conviction But still no DNA match was found. In August 1987, a woman overheard a colleague boasting that he had given a sample for a friend, Colin Pitchfork. Police arrested Pitchfork in September 1987, and scientists found that his DNA profile matched that of the murderer. In this first case, DNA profiling and screening was able to : Link the two crimes, several years apart Secure the conviction of the perpetrator Exonerate an innocent man.

38 Only one-in-a-billionchance that profiles are from two different people, unless they are identical twins.

39 Forensic Entomology

40 Forensic Entomology Involves the study of arthropods, including insects, arachnids, centipedes, millipedes, and crustaceans in criminal or legal cases murder, suicide, rape, physical abuse and contraband trafficking

41 Forensic Entomology In murder investigations, the focus is on: which eggs (eg types of insects) are present their location on the body, and in what order they appear. This is helpful in determining PostmortemInterval (PMI) and Location of death.

42 Forensic Entomology Many insects exhibit: Endemism(occur only in certain places) Phenology(active only in certain season, or time of day). Hence, their presence together with other evidence can also point to times and locations where other events may have occurred.

43 Blow Flies Photo by: L. West/Bruce Coleman Inc Blow flies are first insects to come in contact with dead body great forensic importance Reputedly, they have the ability to smell death from 10 miles away. Blow flies (Calliphoridae) often metallic in appearance, 10-14mm in length. Includes blue bottles; 1200 species Hatching from egg to first larval stage takes from 8hrs to one day. Found in temperate to tropical areas.larvae thrive and pupate in loose, damp litter.

44 Blowflies and Decay Duration of decay process depends on climatic conditions & yearly temperature changes Corpses in summer and rainy season decay at much faster rate than those in winter and spring. Lower temperatures slow down the development of the larvae (maggots). Higher temperature of the corpse due to maggot activity(core maggot mass) itself also speeds up decay.

45 Forensic Psychology Forensic psychology is the intersection between psychology and the justice system. Includes clinical, social, organisational or any other branch of psychology. Important aspects of forensic psychologist s work includes the ability to: testify in court as an EXPERT WITNESS discuss cases that involve issues with the brain or brain damage. They may also deal with issues of whether a person is legally competent to stand trial. assess the state of mind of the defendant at the time of the offence, and to provide an evaluation of the defendant's sanity or insanity (which relates to criminal responsibility) at the time of the offence. provide sentencing and treatment recommendations, or any other information the judge requests, such as information regarding mitigating factors, assessment of future risk and evaluation of witness credibility.

46 And finally

47 Body Farms

48 Body farms A body farm is a research facility where decompositioncan be studied in a variety of settings. Aim -to gain a better understanding of the decomposition process, to develop techniques for extracting information (such as the timing and circumstances of death) from human remains Six such facilities exist in the United States. Largest facility is operated by Texas State University (7 acres).

49 Thank you for listening