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Edmond Locard
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FSCT 7320 midterm
content questions
| Question | Answer |
|---|---|
| Forensic Science | The application of science to those criminal and civil law that are enforced by police agencies in a criminal justice system OR the application of sciences to the law |
| Edmond Locard | demonstrated how scientific method in criminal investigation could be incorporated in a crime lab open police lab in 1910 in Lyon and institute of criminalistics "father of ridgeology" |
| located exchange principle | the perpetrator of a crime will bring something into the crime scene and leave with something from it - both can be used as evidence every contact leaves a trace |
| tuthil introduces | first principles rather than how to approach and apply to most forensic disciplines |
| What is forensic DNA | the process of identifying the type of body fluid found at a scene using DNA technology to assist in addressing the question: who might be the source of this body fluid |
| When was forensic DNA developed | in 1986 by Dr. Alec Jefferys |
| Forensic DNA | recognized as the golden standard in terms of human identification, based on accepted principles of molecular biology and population genetics, Crime scene DNA profile unambiguous identification to reference sample |
| DNA | Deocyribonucleic Acid |
| STRs | Short Tandem Repeats |
| locus | Location of DNA - a single area of interest |
| D8S1179 | DNA on the 8th chromosome that is a single copy at the 1179th marker |
| TPOX | thyroid peroxidase gene |
| TH01 | Tyrosine hydroxyls gene intron 01 |
| STRs allow | for individualization because different people have different numbers of repeats |
| D8S1179: 9,9 | DNA on the eighth chromosome at the 1179th marker with homozygous 9 repeats |
| forensic DNA kits contain | 15 to 21 loci |
| the process of forensic DNA | item found with expected body fluid, DNa extraction from the stain(human cells), quantify the amount of DNA present. |
| PCR process | double stranded DNA is separated, 2 primers complementary to the DNA on each side of the STR locus of interest bind, DNA polymerase starts at primers and complementary nucleotides, results in two strands repeats many times |
| likelihood ratio | prior odds X likelihood ratio = posterior odds |
| forensic science | application of science to law |
| located exchange principle | when two objects contact each other, metrical are transferred from one object to another; the basis for pricing contact by analysis of microscopic evidence |
| how to associate fluid at scene to fluid from suspect | DNA |
| ACEV | analysis - comparison - evaluation- validation |
| class characteristic | a feature of an item that is unique to a group of items. evidence that belongs to a class and is not considered unique |
| individual characteristic | a feature that is unique to a specific item |
| what is luminal used for | identification fo biological evidence |
| how many types of DNA | two - nuclear and mitochondrial |
| the goal of DNA analysis | isolate the FNA by separating it from the majority of the cellular components |
| nuclear DNA | 3 billion bp two meters of DNA |
| mitochondrial DNA | 16569 bo 100's -1000's of copies per cell |
| hard tissues | bigger challenge - cells must be removed from hard tissue - bone marrow (osteoblasts blood producing cells) and teeth (pulp odontoblasts, nerve cells, macrophages) |
| prepare samples for grinding: teeth | remove surrounding bone extract tooth soak in black water and UV irradiate |
| prepare samples for grinding: bones | remove top layer of bone rinse with water and etOH cut multiple cubic sections |
| BCIT lab history | founded in 199 - recognized forensic dna experts accredited leading edge technology over 1000 cases completed |
| how many chromosomes are in the human genome | 46 |
| how Many nucleotides in the human genome | 3.2 billion |
| y-strs | kits which only amplify DNA markers on the Y chromosome - frequently used in sexual assault cases and kinship analysis - single allele at the most loci for a single source |
| DNA from a crime scene matches someone | 1- came from the suspect 2- dna come form someone with the same profile |
| three laws of probability - third law | when two events are independent of one another their probabilities can be multiplied with one another - the probability that they will both occur is equal to a product |
| familial dna testing | used to determine relationships between individuals - dna sharing is determined by how close the relationship is - more closely relation, more DNA is shared - math can be used to determine likelihood relationships |
| innocence project founded | in 1992 in Cardozo school of law |
| innocence project project focused on | exonerating via DNA and preventative law reform redressing wrongful conviction cases and pooling knowledge and resources |
| exoneration definition | when a person who has been convicted of a crime is officially cleared based on new evidence of innocence |
| problems with wrongful application of forensic science | unreliable or invalid forensic evidence, misleading expert testimony, practitioner mistakes, misconduct by forensic analyst, testimony that has since been undermined by scientific advancements. |
| DNA is scientifically sound based on NAS report | biological explanations for individual-specific findings, 13 STR loci used to compare DNA samples selected, probabilities of false positives have been explored and quantified, the laboratory procedures are well specified and subject to validation standard |
| false or misleading analysis practices | bite mark, firearms identification, footwear, microscopic hair |
| coroners service mission | the coroners service is committed to conducting a thorough independent examination of the factors contributing to death in order to improve community safety and quality of like of British Columbia |
| what is a coroner | the coroner is an independent investigator who clarifies the circumstances of death for the public record, fact not fault finding, makes recommendations to precent future loss of life, classify death, reports to chief coroner |
| purpose of investigation | who where when how by what means -> classification -> recommendations |
| a coroners investigation is | fact finding - impartial and objective - independent of influence or bias |
| police vs coroner | police - collect evidence to solve crime or determine criminalist - take primary role in homicide investigations coroner - establish cause and manner of death - take primary role in non criminal deaths |
| pathologists | pathologist need to be registered with royal college of physician and surgeons of canada to practice - BCCS agreed to have pathologist conduct autopsies when requested by a coroner |
| coroner investigative triangle | body - at the scene and autopsy scene- information for pathologists family criminal circumstances collect evidence history- medical lifestyle drug |
| coroner notification | law enforcement, hospitals, physicians/med staff, care facilities, families, concerned citizens |
| coroner scene investigation | coroners conduct independent scene investigations - examine the scene is it consistent with information provided - coroners are trained to identify natural and not natural changes to the body - coroners experience at the scene is critical |
| medical history coroner | disease, medical records, gp dvisits, hospital visits, medication, weightless, symptoms |
| recent activities coroner | eating - chocking sleeping -sleep apnea alcohol exercise exposure |
| coroner head to tow exam | thorough head to toe exam and document findings - interpretation of port mortem changes and trauma - assist police with decisions about criminal activity |
| autopsy ordered? | when cause or manner of death cannot reasonably be determined - compliance with policy - when there is forensic interest - when it will tell us something we don't know now |
| lividity | the pooling of blood to the dependent areas of the body after death (reddish purple) - can be fixed or blanching, usually apparent 2 hours after death can become fixed within 8 hours - blood will not pool into an area where the skin is compressed on surfa |
| rigor mortis | enzyme is released into the muscle causing them to stiffen - apparent 2 hours after death - can take up to 12 hours to progress to full rigorous - accelerated in warm temp and stimulants and physical exertion fever and infection |
| adipocere and degloving | the breakdown of fats in the body - occurs in bodies exposed to water or in moist conditions (plastic bags) |
| petechiae | small, pinpoint hemorrhages visible on conjunctiva of lower inner eyelid or on sclera. indicative of asphyxial cause of death - may also be seen in some natural deaths |
| stages of decomposition | early moderate advanced |
| identification of body | vidicl photo is tattoos/scars fingerprints odontology DNA circumstantial |
| medical cause of death | autopsy by a pathologist - sufficient evidence to determine cause without autopsy - family physician determines cause |
| time of death -post mortem interval | cannot be super accurate - many factors affect indicators rigor, lividity, decomposition, cell phones, calendars, medication blister packs |
| by what means - mechanism of death | ie drug overdose |
| classifications of death | natural - disease accidental - unintentional suicide - self inflicted homicide- due to injury inflicted by someone else (neutral term undetermined - insufficient evidence |
| CAD | coronary artery disease |
| MI | myocardial infarction |
| CVA | cerebrovascular accident |
| DVT | deep wein thrombosis |
| PE | Pulmoney Embolism |
| CHF | congestive heart failure |
| sepsis | systemic infection |
| DIC | disseminated intravascular coagulation |
| MSOF | multisystem organ failure |
| ARF/CRF | acute/chronic renal failure |
| HTN | hypertension |
| reasons for undetermined death | extensive decomposition skeletal remains negative findings suicide vs accident |
| history of forensic entomology | china 10th century Europe 1850s Britain 1930 North America 1970 |
| North American forensic entomology | American board of forensic entomology 1996 19 board certified entomologists |
| clasped time since death | need to know when - make or break alibi - exonerate the innocent - aids in identification of the body - points investigation into correct time frame |
| methods of estimating time since death | dipteran larval development - hours days week successional colonization of insects - months to years |
| larvae development | maggots - attracted immediately after death |
| estimation of time since death | oldest maggots, temperature, species - how long does it take that species to get to that stage then can give minimum |
| successional ecology | rapidly changing ecosystem, body goes through rapid biological, chemical and physical changes - attractive to predictable sequence of insects - varies with habitat season geographic area etc. |
| body moved how can you tell by insects | site one insects different from site two - points to original death scene |
| maggot therapy | remove dead tissue cell for cell - removes necrotic tissues pus bacteria - secrete antibiotics - increases granulation |
| infestation inside body | pseudo-myiasis - ingested eggs or larvae rectal-myiasis - larvae entering anus |
| poaching | same techniques can be applied |
| different bugs than expected succession / different stages | may be because body was concealed then murderer came back and opened it to bug access |
| after fire what is left of bugs | adult blow flies terneral blow flies empty pup aria living pupae wandering third install feeding third instars- all insects dead but all identifiable - after entire house burned maggots pupae and pup aria intact |
| ridgeology | the study of the uniqueness of the friction skin and its use for personal identification - David |
| for ridgeology | need to understand how friction skin persists responds to injury mechanics of touch |
| three layers of skin | epidermis dermis hypodermis |
| what do layers of skin do | provide protective barrier, regulate body temp, sensation, excretion, immunity, blood reservoir, and synthesis of vitamin D |
| epidermis | layered tissue that must constantly replace cells lost at the surface mainly through exfoliation - continually regenerating cells - comprised of keratinocyte cells -and melanocytes langerhans cells and Merkel cells |
| two types of skin | smooth and friction |
| smooth skin | has hair, sebaceous glands, sweat glands, and no friction ridges |
| friction skin | (volar skin) - inner surface of fingers palms and bottoms of feet - may appear lighter - no sebaceous glands - sweat glands only - completely covered in friction ridges |
| dermis | network of cells fibres blood vessel gelatinous material - feeds and support the epidermis and protects the internal body - fibrils secure the dermis to the epidermis via the basement membrane zone - on the surface of the dermis are blunt dermal papillae |
| hypodermis | layer of fatty tissue below dermis - serves as energy reserve, provides cushion, contours the body, allows for movement of skin over underlying structures - connected to dermis through interlocking fibres |
| finger pattern recognition | delta - triangle 0 area on the friction ridges where three ridge systems meet the point on the friction ridge at or nearest to the point of divergence of two types lines and located at or directly in front of the divergence |
| delta | outer focal point located below and to the side of the pattern - triangular - ridges from the delta tend to surround the centre of the pattern |
| core | the approximate centre of the pattern |
| patterns | arch - plain tended loop - ulnar radial whorl - plain double loop central pocket loop accidental |
| arch plain | a fingerprint pattern in which the friction ridges enter on one side of the impression and flow, or tend to flow, out the other side with a rise or wave in the centre |
| arch tented | a type of finger print pattern that possesses either an angle, an upthrust, or two of the three basic characteristics of the loop |
| loop ulnar/ radial | a type of pattern one or more friction ridges enter upon either side recurve touch or pass an imaginary line in between delta and core and flow out on the same side the friction ridges entered |
| whorl plain | a type of fingerprint pattern that consists of one or more friction ridges which makes a complete circuit with two deltas and at least one recurving friction ridge within the inner pattern area is cut or touched |
| whorl double loop | a type of fingerprint pattern that consists of two separate loop formations with two separate and distinct sets of shoulders and two deltas |
| the premises of finger printing | friction ridges develop on the fetus in their definitive form before birth - friction ridges are persistent throughout life expert for permanent scaring |
| the premises for fingerprinting | the specific friction patterns and the details in small areas of friction ridges are unique and never repeated - overall friction ridge patterns vary within limits which allow for classification |
| the philosophy of fingerprinting | friction ridge identification is established through the agreement of friction ridge formations in sequence having sufficient uniqueness to identify |
| what is a fingerprint | an impression made by the ridges of skin on a finger or thumb on a surface - these ridges assist in gripping or obtaining traction. these areas are referred to as friction skin and are found on our hands and feet |
| types of fingerprints | latent finger print - not easily seen by the naked eye and requires development to be visualized visible - impression that is plainly visible due to transfer of visible material moulded- a fingerprint impression that retains a 3D shape in a surface |
| Finger print analysis | determine if the impression is suitable for comparison |
| factors to consider in fingerprint analysis | anatomical factors - substrate - metric - development medium - deposition pressure - lateral/pressure distortion - clarity - tolerance |
| fingerprint anatomical factors | how the object is handled and the way the print was deposited - may assist in digit determination |
| fingerprint substrate | the substrate is the type of surface on which the impression is located - the type of substrate impacts the appearance of the fingerprint |
| fingerprint matrix | what material or medium was deposited on the substrate by the finger - often sweat oils or contaminance |
| fingerprint development technique | what method was used to make the finger print visible - can be developed by optical physical or chemical techniques - reagents can be used in a sequence need to consider type of residue suspected texture type and condition of substrate |
| fingerprint powders | application of fine particles that physically adhere to sweat and oil components in the latent fingerprints - choice of powder depend on adhesion quart and contrast to the substrate |
| fingerprint deposition pressure | the downward pressure exerted by the finger on contact with the substrate - fingers are curved and flexible and when they make contact pressures may vary throughout the impression that is left behind |
| fingerprint lateral/pressure distortion | the movement of the finger and the flexibility of the ridges while - coming into contact- during contact and leaving the surface |
| fingerprint clarity | the visual quality of the friction ridge level 1- overall ridge flow or pattern type level 2- specific ridge paths, major path deviations level 3 - ridge structures and their relative arrangements |
| level 1 detail fingerprint | the overall ridge flow or pattern type - cannot identify but can exclude |
| level 2 detail fingerprint | the specific ridge paths major ridge path deviations - can identify and exclude |
| level 3 detail fingerprint | the ridge structures and their relative arrangements - cannot exclusively identify or exclude |
| fingerprint tolerance | taking into account all the analysis factors - the amount of variation in appearance of friction ridge features to be allowed during a comparison |
| finger print tolerance | high medium and low based on the quality and quantity of detail in a particular area |
| comparison fingerprint | accomplished through side by side observation of all available levels of detail |
| evaluation and conclusion finger print | a quantitative and qualitative evaluation to determine if there is agreement of friction ridge characteristics - having sufficient uniqueness to identify conclusion - the outcome of the evaluation - identification exclusion or inconclusive |
| verification fingerprint | the interpretation of the evidence by a certified forensic identification employee following an opinion |
| forensic science | the application of scientific knowledge and methodology to solve legal problems and criminal investigations |
| forensic identification unit | not scientists - police officers who are technicians that employ various techniques based in science to gather evidence for crime scenes |
| what evidence do ident collect | photographs - fingerprints - footwear impressions - tool mark impressions - firearms and ammunition - blood stain evidence - hair fibre - specialty forensic evidence entomology odontology etc. |
| what are ident duties | document crime scenes through photos and writing - locate preserve collect and examine evidence from crime scenes - maintain continuity of evidence - prevent contamination - prepare reports relating to evidence - testify in court with respect to evidence |
| what crime scenes do ident attend | break and enter (most common) auto crime - theft from vehicles stolen vehicles and crime vehicles - |
| points of entry and exit | how does it affect analysis of the scene - glass break tempered vs normal physical vs implement: fingerprint and blood forced entry - physical vs implement: fingerprint footwear cars - fingerprint open doors - sliding climbers open areas bodies |
| robberies | bank store street |
| modus operandi | relates to someones habits and often used to assist in determning if there is a link between crimes and crime scenes - could be related to type of crime committed actions during crime who they target time of day point of entry/exit method |
| assaults | document all forms of injuries to individual bruising cuts lacerations abrasions - any associated weapons - assist physicians with reports and court evidence |
| drug and gang investigations | drug trafficking and production - gun trafficking and possession - covert entries |
| major incidents | kidnappings and abductions - extortion -arson - sex assaults and child abuse - homicides - also anything the police is called to possibly |
| crime scene examination ident | locate and secure crime scenes - document crime scene - systematic search (grid line spiral fingertip white light exam and visual search) - collect all physical evidence |
| physical evidence collection sequence | photograph the scene as found - photograph the evidence identified - document exhibit - collect exhibit maintain continuity |
| human identification can be done by | DNA - fingerprints - footwear p physical match - primary function |
| fingerprint powders | general powders magnetic powders fluorescent powders |
| firearm and tool mark impressions | small striation on the bullets from the rifling of the barrel pin marks on the cartridge and from the ejection striations made from tool on various surfaces can be listed to compare against too - microscopes and specialized training |
| trace evidence | paint fibre glass |
| expert testimony | entry of expert opinion (regina vs Mohan) - responsible for educating the court - trained to give expert evidence in fingerprint footwear and physical match - blood pattern analysts |
| types fo blood spatter evidence | passive - drops - transfer -touch surface - velocity/spatter - velocity decreases the size of the satin larger drops fly farther tail points give direction info - shape of blood and use of measurements show location from blood source |
| the foal of identification | ensure the examiner knows the principles that govern the comparison of physical evidence and follow proper scientific methods - philosophies, principles, and procedures that apply to the examination and comparison of physical evidence |
| process of identification | comparison -> opinion -> court |
| what happens in court regarding expert and evidence | evidence belongs neither to the crown not the defence - expert is there to assist the court - heavy responsibility to be impartial and unbiased |
| criminalist | someone working within the field of forensic science who examines physical evidence for the purpose of associating it to other physical evidence |
| criminalistics | the science of individualization. The discipline directed to the recognition, identification and evaluation of physical evidence by application of the natural sciences to law-science matters |
| criminology | the study of criminal behaviour |
| forensic science | is the study and practice of the application of science for the purpose of the law |
| science is | a method of acquiring knowledge - extension of common sense |
| forensic science | is practiced by an examiner who applies the special knowledge of their discipline in a careful, organized, systematic way to discover and evaluate evidence that may be of some value in the solution of crime and the prosecution of offenders/law |
| identify vs individualize | criminal is individualized from his finger prints |
| objective vs subjective | sub - refers to personal perspectives feeling opinions ob - refers to the elimination of subjective perspectives and a process that is purely based on facts |
| uniqueness | the quality of being the only one of a kind - all objects in the universe are unique - expect macro and micro scopic differences |
| analysis | the unknown is reduced to a matter of its properties or characteristics - these properties may be observable or measurable - make a record - unknown always analyzed before known |
| comparison | begins only after the expert has recorded in an unbiased manner the properties of the questioned sample |
| evaluation | similarities or differences evaluated the weight or significance of each determined could these have occurred by chance? -> then final opinion |
| wording for weight of evidence | positive (certainty - highly probable - probable - possible - no basis for comparison |
Created by:
Lucie3t