forensic evidence in sexual assault cases...2012/11/01 · research questions goal 1: to provide a...
TRANSCRIPT
Megan Alderden, Ph.D., Saint Xavier University
Theodore P. Cross, Ph.D., University of Illinois at Urbana-Champaign
Alexander Wagner, M.A. Fisher College
Daniel Bibel, Massachusetts State Police
Marjorie Bernadeau, Boston Police Department
Lisa Sampson, M.S.W, Massachusetts Executive Office of Public Safety and Security
Saijun Zhang, Ph.D., University of Illinois at Urbana-Champaign
Kaitlin Lounsbury, M.A., University of New Hampshire
Brittany Peters, M.S. Massachusetts Executive Office of Public Safety and Security
Forensic Evidence in Sexual Assault Cases -
Preliminary Findings
This research is funded by the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice (2011-WG-BX-0005). The opinions, findings, and conclusions or recommendations expressed in this presentation are those of the author(s) and do not necessarily reflect those of the Department of Justice.
Project Overview
Project goals:
1. To provide a detailed description of forensic evidence in sexual assault cases, including its timing relative to criminal justice outcomes;
2. To examine the relationship of forensic evidence to criminal justice outcomes; and
3. To analyze the impact of forensic evidence in key segments of the sample: cases with child victims, cases with stranger assailants, and cases with SANEs conducting the examination.
Research Questions
Goal 1: To provide a detailed description of forensic evidence in
sexual assault cases, including its timing relative to criminal justice outcomes.
(1)What are the characteristics of sexual assault examinations and do these differ by examiner type?
(2)What is the injury identification rate and does this vary by victim, assault, and examiner?
(3)What is the forensic evidence rate and does this vary by victim, assault, and examiner?
(4)What is the timing related to the availability of forensic evidence?
Sexual Assault Case Outcomes: Case Processing
1. Rennison, 2002
2. Chandler & Torney, 1981; LaFree, 1980
3. Bureau of Justice Statistics, 2010
40% are reported to the police1
40% result in arrest2
50% result in felony charges2
33% result in conviction of
original felony
charge3
Convictability impacts attrition
Sexual Assault Case Outcomes: Types of Evidence
Sexual assault victims have a unique place in the criminal justice system: witnesses and crime scenes
Evidence in sexual assault cases Physical evidence – Photographs of injuries, property, clothing.
Forensic evidence –fingerprints, hair, bodily fluids, fibers.
Improvements in evidence collection Examination techniques to improve injury identification
Analytical techniques to improve DNA extraction
Sexual Assault Nurse Examiners (SANE) programs to improve data collection
Sample
Sampling Procedures Random sample of cases in which a Provider Sexual Crime Report
(PSCR) was collected between 2008 and 2010. Cases involving persons 12 years of age or older. Cases in which a forensic examination occurred in Massachusetts. Original sample pool = 2,731
Final N = 587; 21.5% of the original sampling pool
Data sources
Provider Sexual Crime Report (PSCR) Massachusetts Executive Office of Public Safety and Security
Crime laboratory reports Massachusetts State Crime Lab Boston Police Crime Lab
Crime Laboratory Data PSCR Database
Injury type, frequency, location*
Type of examinations completed*
Type of evidence collected (physical, forensic)*
Date/time of evidence kit collected
Date/time kit arrival to lab
Date/time of report of lab results
Laboratory results
*Reflects information obtained from the forensic examination forms available at the crime lab
Victim age, sex, race/ethnicity
Location of assault (city and surroundings)
Location/Date/time of exam
Exam provider (SANE/non SANE)
Number of assailants
Assailant-victim relationship
Weapon type
Description of assault
Reported to police
Completion of evidence kit/toxicology
Data Collection
Victim Characteristics
4.1%
95.9%
69.6%
9.0% 16.1%
5.1% 3.6%
0%
20%
40%
60%
80%
100%
Gender Race/Ethnicity
Victim Characteristics
0
5
10
15
20
25
30
35
40
12 17 22 27 32 37 42 47 52 62 90
Fr
eq
ue
nc
y
Age (years)
Mean: 26 years, SD: 11 years Median: 23 years 67.8% of victims were 15 to 30 years of age
Assault Characteristics
80.8%
14.1%
5.1%
87.0%
8.8% 2.2% 2.0%
30.4%
69.6%
0%
20%
40%
60%
80%
100%
Location of Assault Number of Assailants Relationship
Assault Characteristics
26.7%
43.8%
18.4% 11.9%
89.1%*
18.7%
39.1%
28.5%
0%
20%
40%
60%
80%
100%
Threat/Force Penetration / Sex Act
* Females only
Exam Characteristics
SANE, 69.0%
Non-SANE, 31.0%
Exam Characteristics
0
1
2
3
4
5
6
7
8
9
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 20 21 22 23 24 25 28 38 41
Number of Photos of Non-Genital Injuries
13.6% had at least one photograph of non-genital injuries taken SANE nurses took significantly more photographs
Exam Characteristics
28.4%
46.5%
72.2%
58.4%
42.3%
89.3%
62.4%
0%
20%
40%
60%
80%
100%
Exam Characteristics
98.7% 97.7%
81.5% 84.2%
96.3% 95.9% 95.0%
69.6% 66.3%
0%
20%
40%
60%
80%
100%
Exam Characteristics
68.4%
85.6%
53.5%
74.6% 81.1%
97.0%
79.8%
45.2%
0%
20%
40%
60%
80%
100%
120%
Clothing taken* Head haircombing**
Pubic haircombing***
Additionalswabs***
SANE Non-SANE
* p = < .05; ** p = < .01; *** p = < .001
Injury Identification – Non-Genital Injuries
0
10
20
30
40
50
60
70
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 19 21
22
25
29
30 31
33
39
44
87
Fr
eq
ue
nc
y
Number of injuries
53.0% victims had non-genital injuries Median=4 injuries Black and Hispanic significantly less likely than whites to have any injuries noted (37.0% and 43.8% versus 56.6%)
Injury Identification – Genital Injuries
0
5
10
15
20
25
30
35
40
45
50
Fr
eq
ue
nc
y
Number of injuries to genital structures
41.1% of victims had genital injuries* SANE examiners identified significantly more genital injuries than non-SANE
*Includes: Swelling, redness, abrasion, or tearing to any genital structure
Injury Identification – Female Genital Injuries
8.1% 7.6% 5.9%
16.0%
7.1%
11.1% 8.8%
18.3%
14.0%
20.1% 19.5%
0%
5%
10%
15%
20%
25%
30%
Injury to Specific Female Genital Structures
Injury Identification – Genital Injuries
18.4%
13.3%
21.8%
17.1%
9.9%
4.3%
10.3%
4.9%
0%
5%
10%
15%
20%
25%
Labia minora+ Periurethral tissue(vestibule)*
Posteriorfourchette*
Fossanavicularis**
SANE Non-SANE
+ p = .051; * p < .05; **p < .01.
Availability of Forensic Evidence
27.6% 34.7%
59.3%
39.5%
86.9%
0%
20%
40%
60%
80%
100%
Blood Saliva Semen Otherbiological
Biologicalevidence (all)
Availability of Forensic Evidence
40.9% 37.9%
8.3%
17.5%
0%
10%
20%
30%
40%
50%
DNA profile Match tosuspect
Match to othercase
Match toconvict
Cases with DNA Profile Cases w/ Biological
Evidence
Availability of Forensic Evidence
61.1%
43.4% 38.9%
56.6%
0%
10%
20%
30%
40%
50%
60%
70%
Non-stranger Stranger
No DNA Profile Yes - DNA Profile
p = .004
Time from Exam to Police Report
0
2
4
6
8
10
12
.00
7.0
014
.00
20
.00
26
.00
32
.00
39
.00
45
.00
51.
00
58
.00
64
.00
70
.00
77
.00
85
.00
91.
00
98
.00
105
.00
112
.00
118
.00
125
.00
138
.00
152
.00
163
.00
172
.00
194
.00
22
7.0
03
15.0
04
57
.00
Fr
eq
ue
nc
y
Days
Median: 63 days 25.8% within 33 days 75.2% within 105 days 90.4% within 162 days
Time from Exam to Arrival at Lab
0
5
10
15
20
25
30
35
40
45
.00
3.0
06
.00
9.0
012
.00
15.0
018
.00
21.
00
24
.00
27
.00
30
.00
33
.00
36
.00
39
.00
44
.00
48
.00
52
.00
56
.00
61.
00
67
.00
76
.00
81.
00
97
.00
117
.00
132
.00
172
.00
33
0.0
04
10.0
0
Fr
eq
ue
nc
y
Days
Median: 8 days 28.9% arrived within 4 days 75.7% arrived within 18 days 90.0% arrived within 45 days
Time from Arrival at Lab to Report to Police
0
2
4
6
8
10
12
0.0
0
6.0
0
12.0
0
18.0
0
24
.00
30
.00
36
.00
42
.00
48
.00
55
.00
61.
00
67
.00
73
.00
81.
00
88
.00
97
.00
103
.00
110
.00
120
.00
135
.00
154
.00
168
.00
195
.00
27
3.0
0
35
7.0
0
Fr
eq
ue
nc
y
Days
Median: 44.5 days 25.6% - reported to police within 21 days 75.1% - reported to police within 87 days 90.2% - reported to police within 131 days
Discussion
Examination Completeness SANE nurses photographed more often and were significantly more
likely to complete additional swabs during the exam. Non-SANE medical personnel were more likely to include hair and
pubic hairs combings and include clothing.
Injuries
Non-Genital Injuries—53.0% of cases No differences by examiner type, but differences by race/ethnicity.
Genital Injuries—41.1% of cases
SANE nurses were significantly more likely to identify genital injuries overall.
SANE nurses were significantly more likely to identify injuries on several specific female genital structures.
Discussion
Forensic Evidence 86.9% of cases had biological evidence
40.9% of cases with biological evidence had DNA profile generated
DNA matched the suspect in 27.9% of these cases (7.6% of total sample with data available)
Cases involving strangers were more likely to have a DNA profile generated by the crime labs.
Short time periods between examination, arrival at the lab, and reporting back to the police appear to be the norm.
Next Steps
1. Continuing to exam the evidence collected in these sexual assault cases.
2. Examining the relationship of forensic evidence to criminal justice outcomes.
Linking the forensic and medical examination data to the Massachusetts NIBRS data and Boston Police data
3. Examining the effect of forensic evidence in key segments of the sample: cases with child victims, cases with stranger assailants, and cases with SANEs conducting the examination.
Contact Information
Theodore P. Cross, Ph.D. University of Illinois at Urbana-Champaign