Ac*vity Level Interpreta*on Of Forensic Evidence. Some defini*ons. NCSTL BJA Atlanta, August 2012

Transcription

1 Ac*vity Level Interpreta*on Of Forensic Evidence NCSTL BJA Atlanta, August 2012 Some defini*ons Offender: the person, who really commined a crime Suspect: a person thought to have commined a crime Trace: par*al/degraded material recovered/ observed on a crime scene/vic*m/suspect Control (exemplar): material obtained from a crime scene/vic*m/suspect in controlled condi*ons 1

2 Use of traces in Criminalis*cs Crime Scene(s) Trace vs. Trace Trace vs. Control Vic*m(s) Suspect(s) Use of traces in Criminalis*cs Trace Observe / Recover Crime scene Intelligence Search for poten*al suspect(s) / similar vic*m(s) or crime scene(s) Examine / Analyze Laboratory Compare with control material from suspect(s) / similar vic*m(s) or crime scene(s) Evalua*on 2

3 Use of traces in Criminalis*cs - Example Stain on crime scene Recover Crime scene Intelligence Obtain DNA profile Laboratory Evalua*on Search suspect in DNA database Compare with profile from suspect Use of traces in Criminalis*cs - Example Stain on suspect Recover Crime scene Intelligence Obtain DNA profile Laboratory Evalua*on Search unresolved cases in DNA database Compare with profile of vic*m 3

4 Use of traces in Criminalis*cs - Example Shoeprint on crime scene Recover Crime scene Intelligence Determine brand/wear Laboratory Evalua*on Search in shoe sole database for suspect / similar scenes Compare with shoes from suspect Evalua*on of traces in Criminalis*cs SOURCE Offender Suspect Goal is to figure out whether the offender and the suspect are one and the same person 4

5 Evalua*on of traces in Criminalis*cs SOURCE Offender Suspect OBJECT Trace Exemplar Evalua*on of traces in Criminalis*cs SOURCE Offender Suspect OBJECT Trace Exemplar FEATURES Characteris*cs Characteris*cs 5

6 Evalua*on of traces in Criminalis*cs SOURCE OBJECT Offender Trace Suspect 1 st key element: determina*on of similarity between characteris*cs observed on the trace and on the Exemplar control FEATURES Characteris*cs Characteris*cs Evalua*on of traces in Criminalis*cs SOURCE OBJECT Offender Trace Suspect Does a match indicate that the suspect and the offender are the same person? Exemplar FEATURES Characteris*cs Characteris*cs 6

7 Evalua*on of traces in Criminalis*cs SOURCE Offender Suspect Iden=ty of source OBJECT Trace 2 nd key element: logical inference Exemplar Comparison FEATURES Characteris*cs Characteris*cs Evalua*on of traces in Criminalis*cs - Example 2 key elements: Determina*on that 2 objects (trace and exemplar) are the same How do we do this? Logical inference What do we mean by logical inference? 7

8 Evalua*on of traces in Criminalis*cs - Example Example: A bank is robbed at gun point An eyewitness sees a man with blue skin walking out of the bank and driving away A suspect is arrested based on some unrelated informa*on The suspect has blue skin Are the suspect and the man walking out of the bank the same person? Evalua*on of traces in Criminalis*cs - Example SOURCE Man walking out of bank Suspect OBJECT Physical appearance Physical appearance FEATURES Blue skin Blue skin 8

9 Evalua*on of traces in Criminalis*cs - Example SOURCE OBJECT Man walking out of bank Physical appearance How do we determine the match? 1) Exact same blue? 2) Tolerance levels? Suspect Physical appearance FEATURES Blue skin Blue skin Evalua*on of traces in Criminalis*cs - Example SOURCE Man walking out of bank Suspect OBJECT Physical appearance Skin color corresponds, so what? What are we missing? Physical appearance FEATURES Blue skin Blue skin 9

10 Evalua*on of traces in Criminalis*cs - Example SOURCE OBJECT Man walking Suspect out of bank What makes this evidence different if we are in 1) State College, PA Physical 2) Atlanta, GA Physical appearance 3) In Bluemanland appearance FEATURES Blue skin Blue skin Evalua*on of traces in Criminalis*cs - Example SOURCE OBJECT Man walking Suspect out of bank The strength of the evidence depends on the Physical number of individuals Physical appearance with blue skin in the area! appearance FEATURES Blue skin Blue skin 10

11 Evalua*on of traces in Criminalis*cs - Example 2 key elements: Determina*on that 2 objects (trace and exemplar) are the same How do we do this? Objec*ve or subjec*ve determina*on by a trained and competent forensic scien*st Logical inference What do we mean by logical inference? Evalua*on of the strength of the evidence by the considera*on of the number of alterna=ve possible sources in a given popula=on Evalua*on of traces in Criminalis*cs - Example II Example: A bank is robbed at gun point A latent print is developed from a note handed by the offender to the teller A suspect is arrested based on some unrelated informa*on The control print from the suspect are compared to the latent print Are the suspect and the robber the same person? 11

12 Evalua*on of traces in Criminalis*cs Example II SOURCE Robber Suspect OBJECT Latent print Control prints FEATURES Fric*on ridge features Fric*on ridge features Evalua*on of traces in Criminalis*cs Example II SOURCE OBJECT Robber Latent print Suspect How do we determine the match? 1) Exact same features? 2) Tolerance levels? Control prints FEATURES Fric*on ridge features Fric*on ridge features 12

13 Fingerprint Comparison Fingerprint Comparison 13

14 Evalua*on of traces in Criminalis*cs Example II SOURCE Robber Suspect OBJECT Latent print Fric*on ridge corresponds, so what? What are we missing? Control prints FEATURES Fric*on ridge features Fric*on ridge features Evalua*on of traces in Criminalis*cs Example II SOURCE Robber Suspect OBJECT Latent print How do we infer that the source of the two prints is the same person? Control prints FEATURES Fric*on ridge features Fric*on ridge features 14

15 Individualisa*on fallacy Individualisa*on fallacy 15

16 Individualisa*on fallacy Individualisa*on fallacy 16

17 Individualisa*on fallacy Individualisa*on fallacy 17

18 Evalua*on of traces in Criminalis*cs Example II SOURCE OBJECT Robber Suspect What makes this evidence different if: 1) Suspect lives 2 blocks away 2) Suspect lives 2000 mi away Latent print 3) Suspect lives in Europe Control and prints AFIS hit comes from US Visit FEATURES Fric*on ridge features Fric*on ridge features Evalua*on of traces in Criminalis*cs Example II SOURCE OBJECT Robber Suspect The strength of the evidence depends on the number of individuals Latent print with similar fric*on ridge Control! prints FEATURES Fric*on ridge features Fric*on ridge features 18

19 25 Individualisa*on fallacy Strength Log10 of the LR (H p evidence ) Number of minutiae Number of minu=ae LRs for corresponding marks and prints Evalua*on of traces in Criminalis*cs - Example III Example: A bank is robbed at gun point A cigarene bun is recovered inside the bank A suspect is arrested based on some unrelated informa*on DNA on the cigarene bun is compared with DNA from the suspect Are the suspect and the robber the same person? 19

20 Evalua*on of traces in Criminalis*cs Example III SOURCE Robber Suspect OBJECT How do we determine the match? 1) Exact same features? Reference CigareNe bun 2) Tolerance levels? DNA FEATURES Allelic profile Allelic profile Evalua*on of traces in Criminalis*cs Example III 20

21 Evalua*on of traces in Criminalis*cs Example III Evalua*on of traces in Criminalis*cs Example III SOURCE Robber Suspect OBJECT How do we infer that the source of the two DNA is Reference CigareNe bun the same person? DNA FEATURES Allelic profile Allelic profile 21

22 Evalua*on of traces in Criminalis*cs Example III SOURCE OBJECT Robber Suspect The strength of the evidence depends on the number of individuals Reference CigareNe bun with similar allelic profile! DNA FEATURES Allelic profile Allelic profile Evalua*on of traces in Criminalis*cs Example III SOURCE OBJECT Robber Suspect Pick and choose your sta*s*cal model from 1/10,000s to 1/30 millions Reference CigareNe bun for the same profile DNA FEATURES Allelic profile Allelic profile 22

23 Evalua*on of traces in Criminalis*cs - Examples 2 key elements: Are the trace and control objects the same? Objec*ve or subjec*ve determina*on by a trained and competent forensic scien*st Fingerprint comparison DNA comparison HW, toolmarks/firearms, fibers, glass, paint, shoeprints How many other source could have originated the trace? Evalua*on of the strength of the evidence by the considera*on of the number of alterna=ve possible sources in a given popula=on Sta*s*cal data and model Evalua*on of traces in Criminalis*cs - Examples Evalua*on at source level: Physical appearance: How well does skin color correspond? How many other individuals have same feature? Fingerprint How well do latent and control correspond? How many other individuals have similar fric*on ridge skin? DNA How compa*ble are trace and control allelic profiles? How many other individuals could have contributed? 23

24 Evalua*on of traces in Criminalis*cs - Examples Evalua*on at source level: Physical appearance: How well does skin color correspond? How many other individuals have same feature? Fingerprint How well do latent and control correspond? How many other individuals have similar fric*on ridge skin? DNA What are we missing? How compa*ble are trace and control allelic profiles? How many other individuals could have contributed? Evalua*on of traces in Criminalis*cs - Examples What if the man with blue Evalua*on at source skin level: was seen exi*ng the Physical appearance: bank 5 minutes before the robbery? How well does skin color correspond? How many other individuals have same feature? Fingerprint How well do latent and control correspond? How many other individuals have similar fric*on ridge skin? DNA How compa*ble are trace and control allelic profiles? How many other individuals could have contributed? 24

25 Evalua*on of traces in Criminalis*cs - Examples Evalua*on at source level: Physical appearance: How well does skin color correspond? How many other individuals have same feature? wrinen? Fingerprint How well do latent and control correspond? How many other individuals have similar fric*on ridge skin? DNA What if the latent print was lel before the note was How compa*ble are trace and control allelic profiles? How many other individuals could have contributed? Evalua*on of traces in Criminalis*cs - Examples Evalua*on at source level: Physical appearance: How well does skin color correspond? How many other individuals have same feature? Fingerprint How well do latent and control correspond? was lel prior to the anack? How many other individuals have similar fric*on ridge skin? DNA What if the cigarene bun How compa*ble are trace and control allelic profiles? How many other individuals could have contributed? 25

26 Evalua*on of traces in Criminalis*cs - Examples Evalua*on at source level: Physical appearance: How well does skin color correspond? How many other individuals have same feature? Fingerprint on the relevance of the How well do latent and control correspond? How many other individuals have similar fric*on ridge skin? DNA We are missing informa*on forensic evidence! How compa*ble are trace and control allelic profiles? How many other individuals could have contributed? Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Ac*vity level Crime level 26

27 Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Determina*on whether the DNA came from Mr A Ac*vity level Determina*on whether Mr A had intercourse with the vic*m Crime level Determina*on whether Mr A raped the vic*m Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Relevance Determina*on whether the - Type DNA came of biologic from material Mr A Ac*vity level - Amount of biologic material - Loca*on of trace on the vic*m Determina*on whether Mr A had intercourse with the - Ac*vity of the vic*m vic*m - Contamina*on Crime level Determina*on whether Mr A raped the vic*m 27

28 Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Determina*on whether the DNA came from Mr A Ac*vity level Determina*on whether Mr A had intercourse with the vic*m - Defini*on of offenses Crime level - Other evidence / results of inves*ga*on Determina*on whether Mr A raped the vic*m Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Determina*on whether the shoeprint came from Mr A s shoe sole Ac*vity level Determina*on whether Mr A walked on the scene Crime level Determina*on whether Mr A commined the burglary 28

29 Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Relevance Determina*on whether the shoeprint came from Mr - Number of shoes Mr A owns A s shoe sole - Number of people with access Ac*vity level to the shoes Determina*on whether Mr - A Loca*on walked of on shoeprint the scene Crime level - Time/legi*macy of access Determina*on whether Mr A commined the burglary Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Determina*on whether fibers recovered from vic*m s shirt came from Mr A Ac*vity level Determina*on whether Mr A had a violent contact with vic*m Crime level Determina*on whether Mr A assaulted the vic*m 29

30 Levels of interpreta*on of traces in Criminalis*cs 3 levels Source level Determina*on whether fibers recovered from vic*m s Relevance shirt came from Mr A - Number of corresponding fibers Ac*vity level - Loca*on of corresponding fibers Determina*on whether Mr - Timeframe A had a violent contact with vic*m Crime level Determina*on whether Mr A assaulted the vic*m Evalua*on of traces in Criminalis*cs 4 key elements: Source Are the trace and control objects the same? How many other source could have originated the trace? Ac*vity Is the loca=on/=ming/amount of trace compa=ble with the alleged ac=vity? Where, how, when and why was this trace recovered in the first place? Is there another, reasonable, explana=on for a legi=mate presence of the trace? Who had access to the trace/support to the evidence prior to the offence 30

31 Criminalis*cs - Example An individual is murdered and found in a pool of blood A (small) blood stain is found on the shoe of a suspect The blood stain shows a mixture of two DNA profiles The suspect is charged (based on DNA and other non- forensic evidence) Criminalis*cs - Example 1 st key element: Allelic profiles (rela*ve quan*ty and An designa*on) individual are compa*ble is murdered with a and found in a pool of mixture blood from the vic*m and the suspect A (small) blood stain is found on the shoe of a suspect The blood stain shows a mixture of two DNA profiles The suspect is charged (based on DNA and other non- forensic evidence) 31

32 Criminalis*cs - Example 1 st key element: Allelic profiles (rela*ve quan*ty and An individual 2 key element: designa*on) are compa*ble is murdered with a and found in a pool When considering the vic*m s profile, of mixture blood from the vic*m and the the probability to have that par*cular suspect A (small) mixture blood if somebody stain else is found than the on the shoe of a suspect contributed is in the one in suspect millions The blood stain shows a mixture of two DNA profiles The suspect is charged (based on DNA and other non- forensic evidence) Criminalis*cs - Example 1 st key element: Allelic profiles (rela*ve quan*ty and An individual 2 key element: designa*on) are compa*ble is murdered with a and found in a pool When considering the vic*m s profile, of mixture blood from the vic*m and the the probability to have that par*cular suspect A (small) mixture blood if somebody stain else is found than the Based on 1 on the shoe of a suspect contributed & 2 is in the key elements: one in suspect millions The blood How stain doomed shows a is mixture the suspect? of two DNA profiles The suspect is charged (based on DNA and other non- forensic evidence) 32

33 Criminalis*cs - Example 1 st key element: Allelic profiles (rela*ve quan*ty and An individual 2 key element: designa*on) are compa*ble is murdered with a and found in a pool When considering the vic*m s profile, of mixture blood from the vic*m and the the probability suspect 3 rd key element: to have that par*cular A (small) mixture Loca*on blood if somebody stain and amount else is found than of blood: the on the shoe of a suspect suspect - 1 contributed (small) stain is vs. in pool the one of blood in on the millions crime scene The blood - on stain one of shows approx. a 10 mixture pairs that of the two DNA profiles suspect could have worn The suspect is charged (based on DNA and other non- forensic evidence) Criminalis*cs - Example 1 st key element: Allelic profiles (rela*ve quan*ty and An individual 2 key element: designa*on) are compa*ble is murdered with a and found in a pool When considering the vic*m s profile, of mixture blood from the vic*m and the the probability suspect 3 rd key to have that par*cular A (small) mixture blood if 4somebody th key element: element: Loca*on stain and amount else is found than of blood: the on the shoe of a suspect contributed Legi*macy: suspect - 1 (small) stain is vs. in pool the one of blood in on the millions - Stain is definitely human blood crime scene - Stain definitely shows a mixture of profile The blood - on stain one of shows approx. a 10 mixture pairs that of the two DNA However profiles suspect could have worn - Whose contributor gave the blood? Vic=m The suspect or is suspect? charged (based on DNA and - Swab from inside the shoes show that both other non- forensic individuals evidence) wore the shoes - Stain on suspect s shirt shows suspect s blood 33

34 Criminalis*cs Example II A 6 years old girl lives with her grand- mother and step grand- father She calls her mother at 11:30pm Tells her step grand- father put a finger and licked [her] private Mother drives her home, then calls the police, then goes to hospital DNA on rape kit shows only DNA of the girl Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged Criminalis*cs Example II 34

35 Criminalis*cs Example II - Bias Criminalis*cs Example II - Bias 35

36 Criminalis*cs Example II - Bias Criminalis*cs Example II Bias - Examina*on was clearly biases A towards 6 years prosecu*on old girl lives with her grand- mother and step - Stain grand- father on the underwear She - Comments calls her from mother State Trooper at 11:30pm - Allelic Tells designa*on her step grand- father of STR put a finger and licked [her] private Mother drives her home, then calls the police, then goes to hospital DNA on rape kit shows only DNA of the girl Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged 36

37 Criminalis*cs Example II 1 st key element: A Presump*ve 6 years old test girl on lives underwear with her grand- mother and step is compa*ble grand- father with saliva She Allelic calls profile her of mother STR and at Y- STR 11:30pm are Tells compa*ble her step grand- father with suspect put a finger and licked [her] private Mother drives her home, then calls the police, then goes to hospital DNA on rape kit shows only DNA of the girl Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile her of mother test STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng her step with grand- father with enzymes suspect in diges*ve put a finger system and licked [her] - Allelic private profile of STR (one very weak allele) is also compa*ble with a stuner from allele 13 from vic*m Mother drives her home, then calls the police, - Y- STR profile is also compa*ble with suspect s then goes to hospital brother, nephew and grand- nephew DNA on rape kit shows only DNA of the girl Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged 37

38 Criminalis*cs Example II Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile 3 rd her key of mother test element STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng (loca*on, her step with amount, grand- father with enzymes *me suspect in diges*ve frame): put a finger system and licked [her] - Allelic - Amount: private profile of if prosecu*on STR (one very hypothesis weak allele) is correct, is also DNA compa*ble from vic*m with is a stuner masking from DNA allele from 13 suspect, from vic*m which Mother drives her home, then calls the police, - Y- STR is profile revealed is also when compa*ble targe*ng Y- Chromosome with suspect s then goes to hospital brother - 1 part and in nephew 200 to 1 part in 2000 in other words, can DNA on rape kit shows only DNA of the girl Stain on infinitesimal underwear traces shows Y- DNA profile similar to step grand- father Step grand- father is charged be compa*ble with ac*vity, but can also go as low as 38

39 Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile 3 rd her key of mother test element STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng (loca*on, her step with grand- father with amount, enzymes suspect *me in diges*ve put frame): a finger system and licked [her] - Allelic private profile of STR (one very weak allele) is also compa*ble Mother prosecu*on with a drives her not stuner home, considering? from allele 13 from vic*m then calls the police, - Y- STR then goes what profile to DNA is hospital evidence also compa*ble would carry with suspect s significantly more brother weight? and nephew (remember that we are talking about digital DNA on rape kit shows only DNA of the girl penetra*on ) Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged - loca*on: if prosecu*on hypothesis is correct, what is Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile her of mother test STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng 3her rd key step with grand- father with element enzymes suspect in diges*ve put a finger system and licked [her] - Allelic (loca*on, private profile amount, of STR (one *me very frame): weak allele) is also compa*ble with a stuner from allele 13 from vic*m Mother drives her home, then calls the police, - Y- STR then goes prosecu*on profile is also to hospital not compa*ble considering? with suspect s brother - nobody and nephew checked nails of suspect DNA on rape kit shows only DNA of the girl Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged - loca*on: if prosecu*on hypothesis is correct, what is 39

40 Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile her of mother test STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng 3 4 her nd th key step key with grand- father with enzymes element element suspect in diges*ve put a finger system and licked [her] - Allelic (alterna*ve private profile of explana*on STR (one very for weak ac*vity): (loca*on, amount, *me frame): allele) is also compa*ble - girl is living with a with stuner grandma, from allele step grandpa 13 from & vic*m step Mother drives her home, then calls the police, - Y- STR grand profile uncle is also and compa*ble step cousin with (3 males suspect s with same then goes prosecu*on to hospital not considering? brother Y- STR - nobody and profile ) nephew checked nails of suspect DNA on rape kit shows only DNA of the girl Stain on cousin underwear shows Y- DNA profile similar to step - grand- father girl played for several hours on grandpa s bed Step grand- father is charged - loca*on: if prosecu*on hypothesis is correct, what is - girl went to swimming- pool and showered with step All these ac=vi=es are compa=ble with contamina=on by low quan=ty of DNA from surrounding family Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile her of mother test STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng 3her 4 nd th step key with grand- father with enzymes element suspect in diges*ve put a finger system and licked [her] - Allelic (loca*on, (alterna*ve private profile amount, of explana*on STR (one *me very frame): for weak ac*vity): allele) is also compa*ble Mother - drives could the with her State a stuner home, have from anempted allele 13 then calls to the exclude from vic*m police, - Y- STR then goes prosecu*on contamina*on? profile is also to hospital not compa*ble considering? How? with suspect s brother - nobody and nephew checked nails of suspect DNA on rape kit shows only DNA of the girl Stain on underwear shows Y- DNA profile similar to step grand- father Step grand- father is charged - loca*on: if prosecu*on hypothesis is correct, what is 40

41 Criminalis*cs Example II 1 st key element: A Presump*ve 62years nd key old element test girl on lives underwear with her grand- mother and step is compa*ble (alterna*ve grand- father explana*on): with saliva She Allelic - calls Presump*ve profile her of mother test STR on and underwear at Y- STR 11:30pm is also are Tells compa*ble reac*ng 3her 4 nd th step key with grand- father with enzymes element suspect in diges*ve put a finger system and licked [her] - Allelic (loca*on, (alterna*ve private profile amount, of explana*on STR (one *me very frame): for weak ac*vity): allele) is also compa*ble Mother - drives could the with her State a stuner home, have from anempted allele 13 then calls to the exclude from vic*m police, - Y- STR then goes prosecu*on contamina*on? profile is also to hospital not compa*ble considering? How? with suspect s brother - nobody and nephew checked nails of suspect DNA on - By rape taking kit background shows only samples DNA of on the the underwear girl Stain on and underwear other clothes shows of the Y- DNA girl profile similar to step grand- father Step grand- father is charged - loca*on: if prosecu*on hypothesis is correct, what is Criminalis*cs Example II A 6 years old girl lives with her grand- mother and step Did grand- father alleged ac=vity occur? She Maybe calls her mother at 11:30pm Does Tells the her considered step grand- father forensic put evidence a finger demonstrate and licked anything? [her] private (when considered ra*onally) Mother Not at all drives her home, then calls the police, then Did goes the State to hospital have the opportunity to address the DNA major on weaknesses rape kit shows of their only argument? DNA of the girl Stain Yes, on but underwear they didn t think shows it through Y- DNA profile similar to BoWom step grand- father line, nobody should be charged and Step convicted grand- father based on this charged evidence 41

42 Ac*vity level interpreta*on of forensic evidence 4 key elements/ques*ons How similar are the trace and control samples? How was that determined? How many other sources can produce a trace with the same characteris*cs in a popula*on? Are the loca*on, amount and *meframe compa*ble with the alleged ac*vity? What other ac*vi*es could explain the presence of the trace? Ac*vity level interpreta*on of forensic evidence Not groundbreaking: Based on common sense However: Provides a systema*c framework for the considera*on of forensic evidence What it truly means in the context of the case? Whether what was done made sense? What should have been done? Avoid was*ng *me and resources in unnecessary challenges and private experts. 42