Tactical (S)NA:
Using Affiliation Networks
to Aid Serial Crime Investigations
Deputy Lim
Gisela Bichler
Edgar Larin
Steven Lim
(with the assistance of
Lisa Chavez & Pedro Martinez)
______________
2nd Lt. Larin
Department of Criminal Justice
California State University, San Bernardino
5500 University Parkway, SBDO, 92407
francesco calderoni
What utility does the network approach have
for an ongoing investigation?
completed cases
Italian
mafia
wire taps; court documents (natarajan, bright, leuprecht)
investigatory documents (morselli, bouchard)
aggregates
combined intelligence (malm & bichler)
LE & other sources (kleemans, van de bunt, de poot, sarnecki)
Calderoni, Francesco. 2012. Roundtable at ASC, D.C.
kim rossmo
investigatory failure
cognitive
biases
e.g., tunnel vision,
satisficing
errors in
probability
e.g., coincidences,
conjunction fallacy
organizational
traps
e.g., groupthink,
organizational momentum
Rossmo, D. Kim (2009).Criminal Investigative Failures. CRC Press: New York
Rossmo, D. Kim (2014). Criminal Case Rethinking. Presentation Western Society of Criminology, HI
Organizational momentum, the inability to change
direction in the midst of a major investigation…
shifting focus away from working
hypothesis or “good” suspect
suggestion: projected networks
Rossmo, D. Kim (2009).Criminal Investigative Failures. CRC Press: New York
Rossmo, D. Kim (2014). Criminal Case Rethinking. Presentation Western Society of Criminology, HI
simon demers
When is there enough information to
warrant a criminal inquiry?
find the investigatory tipping point
suggestion: network evolution models
LePard et al. (2014). Challenges in Serial Murder Investigations involving Missing Persons.
Presentation Western Society of Criminology, HI
purpose
test if (S)NA has tactical utility in an investigation
• identify information or change thresholds
• find central actors/places
start with serial case
with known offender
green river killer
18
lengthy case (1982-2001)
shift in investigative focus
w/ temporal variation
16
number of victims
14
12
10
8
6
a conviction
4
2
0
before 6 months 12 months 18 months 24 months post 30
bodies
months
discovered
timeline
vice crackdown
on SEATAC stroll
“john”
arrest
&
recent
divorce
decoys
resume
search home
got DNA
questioned
key source
published
moved
&
married
questioned
&“passed”
polygraph
Gary Ridgway
dating
bodies
found
arrested
1982
1983
25 members
1984
1985
1986
43 member task force
1987
1988
1989
1990
1991
1992
1993 ….
2001
sources
published 1991
(before offender known)
independent public account
(re-interviewed witnesses & visited places)
followed case from beginning
Kim said it was good
did not use…
inclusion criteria
could construct a dyad
April 1983
j
person associated with
a case important place/site
unknown
time stamp for place association
X
70% dyads usable
(151 / 217 )
geographic aggregation
obtained coordinates
aggregated to census
blocks (2000)
Washington
temporal aggregation
All info
JAN-85 – DEC-03
30 Months
JUL-84 – DEC-84
24 Months
JAN-84 – JUN-84
18 Months
JUL-83 – DEC-83
12 Months
JAN-83 – JUN-83
T1
multiple bodies found
in the Green River
JUL-82
DEC-82
6 Months
temporal aggregation
All info
JAN-85 – DEC-03
30 Months
JUL-84 – DEC-84
24 Months
JAN-84 – JUN-84
18 Months
JUL-83 – DEC-83
T2
multiple bodies found
in the Green River
12 Months
JAN-83 – JUN-83
JUL-82
DEC-82
6 Months
temporal aggregation
All info
JAN-85 – DEC-03
30 Months
JUL-84 – DEC-84
24 Months
JAN-84 – JUN-84
T3
18 Months
JUL-83 – DEC-83
12 Months
JAN-83 – JUN-83
multiple bodies found
in the Green River
JUL-82
DEC-82
6 Months
temporal aggregation
All info
JAN-85 – DEC-03
30 Months
JUL-84 – DEC-84
T4
24 Months
JAN-84 – JUN-84
18 Months
JUL-83 – DEC-83
12 Months
JAN-83 – JUN-83
multiple bodies found
in the Green River
JUL-82
DEC-82
6 Months
temporal aggregation
All info
JAN-85 – DEC-03
30 Months
T5
JUL-84 – DEC-84
24 Months
JAN-84 – JUN-84
18 Months
JUL-83 – DEC-83
12 Months
JAN-83 – JUN-83
multiple bodies found
in the Green River
JUL-82
DEC-82
6 Months
temporal aggregation
All info
T6
JAN-85 – DEC-03
30 Months
T5
JUL-84 – DEC-84
24 Months
T4
JAN-84 – JUN-84
18 Months
T3
JUL-83 – DEC-83
T2
12 Months
JAN-83 – JUN-83
T1
multiple bodies found
in the Green River
JUL-82
DEC-82
6 Months
study units
Study Units
Descriptive Categories
People
Victims
Investigatory involvement (e.g., witnesses, body finders)
Suspects
Family and Associates
Places
Body dumpsites
Last seen locations
Material to investigation or combination
Percent
(N)
(88)
56.8
29.6
8.0
5.7
(58)
37.9
44.8
17.2
network generation
affiliation networks
(2 different units)
prostitute #2
prostitute #1
Shared activity
space/node
body
dumpsite
prostitution
stroll
suspect
projecting a network
(deriving a 1-mode network)
actor-to-actor
place-to-place
prostitute #2
prostitute #1
body
dumpsite
prostitution
stroll
suspect
projecting a network
(deriving a 1-mode network)
actor-to-actor
place-to-place
prostitute #2
prostitute #1
body
dumpsite
prostitution
stroll
suspect
results
network stability
change in positional importance
stability
jaccard coefficient
time 2
time 1
D
B
C
A
D
B
C
A
repeated for
the entire
network
proportion
the same
< 20% new network forms …radical shift in focus
20-60% natural evolution … filling in gaps
> 60% too much stability … investigatory stagnation
network stability
actor-to-actor
T3
actors
T2
places
place-to-place
(18 months)
(12 months)
note: jaccard coefficients converted to %
betweenness centrality
standardized probability of sitting between others or joining different
subsets of the network – go between along most efficient path
C B (ni )
C (ni ) 
( g  1)( g  2) / 2
'
B
more likely to be associated with
pairs (of victims)
linked people
Other
Victim
Suspect
Period 1
6 months
24 people
102 unique ties
19% density
T2
12 months
T3
18 months
T4
24 months
T5
30 months
T6
entire investigation
linked people
Other
Victim
Suspect
T1
6 months
39 people
220 unique ties
15% density
Period 2
12 months
T3
18 months
T4
24 months
T5
30 months
T6
entire investigation
linked people
Other
Victim
Suspect
T1
6 months
59 people
424 unique ties
13% density
T2
12 months
Period 3
18 months
T4
24 months
T5
30 months
T6
entire investigation
linked people
Other
Victim
Suspect
T1
6 months
66 people
556 unique ties
14% density
T2
12 months
T3
18 months
Period 4
24 months
T5
30 months
T6
entire investigation
linked people
Other
Victim
Suspect
T1
6 months
76 people
686 unique ties
12% density
T2
12 months
T3
18 months
T4
24 months
Period 5
30 months
T6
entire investigation
linked people
Other
Victim
Suspect
T1
6 months
88 people
1,304 unique ties
18% density
T2
12 months
T3
18 months
T4
24 months
T5
30 months
Period 6
entire investigation
freeman’s betweenness
Suspects
T1
T2
T3
T4
(standardized)
T5
T6
07/82–12/82
07/82–06/83
(12 months)
07/82–12/83
07/82–06/84
07/82–12/84
07/82–12/03
(18 months)
(24 months)
(30 months)
(entire period)
(6 months)
Gary Ridgway
.
0.17
2.54
1.53
1.21
1.16
Bobby Woods
.
.
1.54
0.17
.
0.64
0.20
.
1.08
0.26
1.19
1.45
0.27
0.87
1.35
0.30
0.79
1.31
24
39
59
66
76
88
James M Tindal
Melvyn Foster
People in network
prime suspect Sept. 1982 to 1985
If we ignore Melvyn Foster as a suspect….
Suspects
T1
T2
T3
T4
T5
T6
07/82–12/82
07/82–06/83
(12 months)
07/82–12/83
07/82–06/84
07/82–12/84
07/82–12/03
(18 months)
(24 months)
(30 months)
(entire period)
(6 months)
Gary Ridgway
.
0.048
0.725
0.393
0.238
0.179
Bobby Woods
.
.
.
0.048
.
.
0.053
.
.
0.063
0.316
.
0.063
0.153
.
0.038
0.123
0.267
24
39
59
66
76
88
James M Tindal
Melvyn Foster
People in network
prime suspect Sept. 1982 to 1985
place connectivity
21 nodes
32 ties
8% density
Last Seen
Body Dumpsite
Symbol size shows betweenness centrality. (derived place‐to‐place network)
Period 1
6 months
T2
12 months
T3
18 months
T4
24 months
T5
30 months
T6
entire investigation
place connectivity
32 nodes
64 ties
7% density
Last Seen
Body Dumpsite
Symbol size shows betweenness centrality. (derived place‐to‐place network)
T1
6 months
Period 2
12 months
T3
18 months
T4
24 months
T5
30 months
T6
entire investigation
crackdown on
prostitution stroll by SEATAC
place connectivity
44 nodes
104 ties
6% density
Last Seen
Body Dumpsite
T1
6 months
T2
12 months
Period 3
18 months
T4
24 months
T5
30 months
T6
entire investigation
place connectivity
50 nodes
154 ties
7% density
Last Seen
Body Dumpsite
Symbol size shows betweenness centrality. (derived place‐to‐place network)
T1
6 months
T2
12 months
T3
18 months
Period 4
24 months
T5
30 months
T6
entire investigation
place connectivity
55 nodes
196 ties
7% density
Last Seen
Body Dumpsite
Symbol size shows betweenness centrality. (derived place‐to‐place network)
T1
6 months
T2
12 months
T3
18 months
T4
24 months
Period 5
30 months
T6
entire investigation
place connectivity
58 nodes
284 ties
10% density
Last Seen
Body Dumpsite
Symbol size shows betweenness centrality. (derived place‐to‐place network)
T1
6 months
T2
12 months
T3
18 months
T4
24 months
T5
30 months
Period 6
entire investigation
research findings
brantingham2
influence of social network on choice of activity nodes
(behavioral settings) and thus, spatial behavior
utility of graph theory to understand connectedness
(aggregated activity space)
Brantingham, P. and P. Brantingham (1984). Patterns in Crime. Macmillan. Ch. 12; 9.
Brantingham, P. and P. Brantingham (2008). Crime pattern theory. In Environmental Criminology and
Crime Analysis, R. Wortley and L. Mazerolle (Eds.) Willan. Ch. 5.
practical findings
actor network
•
•
•
•
•
information threshold 18 months
radical shift in suspect centrality
some people never central (outliers)
structurally important victims
additional relationships and actors
obscures key suspect
location network
• stable at 12 months
• variation in centrality of hunting
locations
• shift in centrality of body dumpsites
• some places not connected
• central places
limitations
issues
next steps
geographic aggregation lost
spatial precision
street segments?
missing time reduced no. actors
person-to-person (w/o time)
descriptive statistics
repeated measures ANOVA
case study w/ public info.
collaborate & replicate
take home
betweenness / projected networks
might be useful rethinking cases
test for organizational momentum
select sources
Calderoni, Francisco (forthcoming) Predicting Leadership from Meeting Attendance in
Criminal Networks. In Gisela Bichler & Aili Malm eds. Using Social Network
Analysis to Prevent Crime, Crime Prevention Studies Vol. 28, Lynne Rienner
Publish: Boulder, Colorado
Reichert, David (2004) Chasing the Devil: My Twenty-year Quest to Capture the Green
River. Little, Brown and Company: New York, NY
Rossmo, D. Kim (2000). Geographic Profiling. CRC Press: London New York
Rossmo, D. Kim (2009).Criminal Investigative Failures. CRC Press: London New York
Smith, Carlton and Thomas Guillen (1991). The Search for the Green River Killer: A True
Crime Shocker. Penguin Putnam: New York, NY
State of Washington vs. Gary Leon Ridgway. Prosecutor’s Summary of the Evidence. No.
01-1-10270-9 SEA Superior Court of Washington for King County.
plugs
Disrupting
Criminal Networks
Crime Prevention Studies
Vol. 28
Gisela Bichler & Aili Malm
March 2015
Contributors
Topic
Jean M. McGloin & Zachary Rowan
Gangs and Delinquency
Michael Sierra-Arevalo &
Andrew V. Papachristos
Carlo Morselli, Thomas U. Grund, &
Rémi Boivin
David A. Bright
Francesco Calderoni
Robert R. Faulkner & Eric R. Cheney
David Décary-Hétu &
Dominique Laferrière
Kila Joffres & Martin Bouchard
Stacy Bush & Gisela Bichler
Lucia Summers & Shane D. Johnson
Group Audits and POP
Co-offending
Drug Distribution
Organized Crime
Leaders
Enterprise Conspiracy
Online Criminal Markets
Online Child Exploitation
Terrorist Communications
Space Syntax
Journal of
Contemporary
Criminal Justice
Aili Malm, Gisela Bichler &
Carlo Morselli
March 2015
Contributors
Topic
Jacob Young & Justin Ready
On-officer Cameras
(Diffusion)
Evan McCuish, Martin Bouchard &
Raymond Corrado
Peter Carrington
David A. Bright et al.
Thomas Grund & James Densley
Gisela Bichler, Andrea Schoepfer &
Stacy Bush
Homicide Co-offending
Age & Co-offending
Drug Trafficking
Gangs
Corporate Offenders
Criminology, Criminal Justice, Law and Society
Christian Leuprecht & Andrew Aulthouse
[International Gun Trafficking]
Fall 2014, Volume 15, Issue 3
Sean Everton & Dan Cunningham
[Terror Group Structure]
Forthcoming March 2015, Volume 16, Issue 1
thank you