6th International Conference
on Evidence-Based Policing
Tuesday 9th July 2013
A Homicide Hot Spots Patrol Test in
Trinidad and Tobago
Commissioner of Police (Ag)
Stephen Williams
Trinidad & Tobago
Background
• A sharp increase in the number of homicide cases in
T&T during the last decade
• Over 60% attributed to gang-related activity
• Yet even within high-crime areas, violence in T&T tends
to be concentrated in smaller, micro-level crime places
– a strong justification for hotspot policing
• Cambridge University <> TTPS partnership
Spatial and Temporal Concentrations
of Homicides in T&T
n=1,662
1 Jan 2009 – 21 Jan 2013
Homicide – Month
200
180
160
156
140
120
100
80
60
40
20
0
129
115
Time of Day (n=1,354) – All Divisions
10%
9%
8%
7%
percent
6%
5%
4%
3%
2%
1%
0%
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5
hour of day
Top 4 Divisions (81% of all Homicides)
Port of Spain
Northern
North Eastern
Western
14%
12%
10%
8%
6%
4%
2%
0%
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23
hour of day
0
1
2
3
4
5
Homicide - Day of Week
18%
16%
14%
12%
10%
8%
6%
4%
2%
0%
16.4%
15.5%
14.0%
12.9%
11.9%
14.3%
15.0%
Spatial Concentrations –
Port of Spain as a case study
Aerial view of the hotspot with the highest homicide rate
(n=138 in 4 years)
MOSTLY HANDGUNS!!
Robbery
Shoot/wound
Grand Total
87.52%
84.95%
87.14%
Other firearm
3.32%
3.13%
3.30%
Other weapon
2.64%
4.12%
2.86%
Sawed off shot gun
0.80%
0.49%
0.76%
Shot gun
5.72%
7.30%
5.95%
N
12,818
2,233
15,051
Hand gun
The Trinidad and Tobago Homicide
Hotspots Experiment
Targets and Aims
• Reduce Serious Crime by 50% compared to
control conditions
• Use all 3 “Triple Ts” of Evidence Based Policing
– Targeting the power few
– Testing the Intervention through rigorous science and
– Tracking with GPS tracking and effective management
(station-level Compstat)
Selection of Targets
• All Police Station Districts that have eligible hotspots within their
geographic boundaries
• Top percentile that is responsible for most of crime and disorder in
Trinidad and Tobago
• Excluding Laventille
• Focus heavily on violent crimes (shootings, woundings and
homicides) and overall crime harm index
• Focus indirectly on all other serious street crimes
• Increase legitimacy of T&T Police through effective but fair
procedures
Proposed Program
• Station-Level Compstat Every 14 days
--hearts and minds, targeting predicted crime
• Hot Spot Patrols Hot Times—primarily in vehicles
• Patrol Tracking Maps for Compstat Discussion
• Searches for Guns
• Roadblocks Stop & Search
Process of Random Assignment
1. Rank-Order all T&T Stations according to resources
available (n of vehicles, manpower, etc.) and n of serious
incidents in 12 months (shootings, homicides, woundings)
2. Exclude Besson Street Police Station--all treatment *
3. Exclude stations with fewer than 5 incidents in 12 months
4. Random assignment of stations across districts
creating 24 pairs
______
* Extreme outlier with 188 incidents; next in rank is Morvant Police Station with
49 incidents
Random Assignment - mid range stations
shootings+woundings+homicides +attempted homicides
40
35
38
30
25
25
20
15
16
12
10
13
11
7
5
6
7
6
0
A
B
C
D
E
F
Stations
G
H
I
J
Tracking Patrols
GPS Tracking
1. AVL GPS-based trackers
2. Hand held GPS trackers
3. Crucial: It will help us measure the link
between police presence and crime
4. As crucial: Officers’ safety!
Bi-Weekly Station-Level Compstat
• Common practice in T&T at Division level, but not
yet at station level
• Ongoing feed of data from CAPA
• Winning the hearts and minds of officers with:
1. Positive and negative reinforcements
2. Quick response to issues: Discussing challenges and
obstacles at the tactical level
3. Accountability: ownership of problems at hotspots
by designated officers
Outcomes
1.
2.
3.
4.
N of all crimes
N of homicides
Tankebe’s legitimacy surveys
Crime harm index
Crime Harm Index - Quarterly Totals
25000000
20000000
15000000
10000000
5000000
0
Cameras?
• ….
6th International Conference
on Evidence-Based Policing
A Homicide Hot Spots Patrol Test in
Trinidad and Tobago
Commissioner of Police (Ag)
Stephen Williams
Trinidad & Tobago