An analysis last year of Chicago Police Department deployment data appears to raise questions about whether Chicago police officers are consistently on the street at times when most shootings happen in the city.
The findings show that deployment levels decline during the weekend overnight time periods when shootings are going up.
Those familiar with the documents released to the Tribune said the analysis was a first step toward using real-time data to design a strategy for the thorny and political question of where and when officers should be deployed.
The analysis was completed by the University of Chicago Crime Lab, which relied on historic shooting data and GPS information from police vehicles from the nine-month period between June 2020 and February 2021. Summary information from it was released to the Tribune Aug. 4 as part of an open records request to the Chicago Police Department, which had requested the analysis from the lab.
The department originally received the analysis March 10, 2021. The report drilled down into where and when officers were working in the field and where and when shootings happen.
Several parts of the analysis were heavily redacted, with the department citing officer and community safety as reasons for declining to fully disclose the information. Among the redacted material were specifics on where officers were deployed and where in their districts they spent their time.
The review was part of a larger Workforce Allocation study the lab performed, which included a look at 911 response times as well.
Among the conclusions that were not redacted was that 14% of shootings are happening between midnight and 5 a.m. on Saturdays and Sundays in the city's least safe areas, but just 3.8% of the work hours of Chicago police tactical teams were logged there during that same 10-hour period.
The Chicago Police Department refused to answer specific questions about the analysis or whether it was used to make subsequent deployment decisions. Mayor Lori Lightfoot's office did not respond to a request for comment.
The Tribune asked to speak directly to Chicago police Superintendent David Brown and was given an emailed statement that said the department "regularly reviews and adjusts resources across the Department to enhance public safety and address crime patterns."
The statement also noted that shootings and homicides across the city are down, at least year-over-year. The Workforce Allocation study, however, aimed to not only reduce crime but also build "efficiency, equity, and transparency in patrol staffing" and insulate the deployments from politics or pressure on where cops should work.
"The allocation of police department resources in most US cities is based on the desires and intuition of key decision-makers and often winds up being highly political and unequal," reads a summary the lab issued several months ago about the overall study when they completed the work.
The process is not nimble enough to adjust to crime spikes or shifting crime patterns, it added.
"Too often officers aren't available when and where they're most urgently needed," it said.
Questions surrounding police deployment in Chicago has long been the subject of political debate and speculation, with aldermen, including those in the historically safer parts of the city, demanding more patrols for their neighborhoods and accusing the department of draining their personnel.
At the same time, at least one lawsuit has documented the inequities in response times across Chicago.
The Central Austin Neighborhood Association reached a settlement last year with the city to address "the chronic disparity in police response times to calls from white neighborhoods compared to neighborhoods that are primarily Black and Brown," according to the ACLU of Illinois, which filed the lawsuit.
The court-ordered settlement has forced the city to publish response-time data, but a spokesman for the ACLU said it is too soon to draw conclusions about the data because it remains incomplete.
Experts told the Tribune, however, that the response times, as dealt with in the lawsuit, are just one piece of an overall deployment strategy.
A comprehensive plan is based on where and when crime happens, where and when officers are in the field and their workload.
Some departments set staffing levels after determining how fast they want officers to answer calls for service and how much time they want them to engage proactively with the community, said Darrel Stephens, who has led four police departments and now works as a national policing consultant.
Some large departments, for example, have set targets for officers to respond to emergency calls for service within seven minutes and to spend, on average, 40% of their day on proactive policework, experts have said.
Stephens said he used a similar approach. The combination of having quick response times and being "proactive" is what drives crime and violence down, he said.
Stephens also said he sees no reason not to share such data-driven deployment strategies with the public.
"There is never any reason to keep it a secret in my perspective," he said. "There is no reason why the public shouldn't know where officers are assigned and how many. Why not?"
Chicago Police Department officials, when asked to address how they make deployment decisions, typically refer to some 50 hot spots that have been targeted for more resources based on shootings.
At the same time, Brown has repeatedly announced the shifting of resources to problem areas, like downtown or the CTA, in the wake of violence.
The department has also faced criticism for canceling regular days off for officers to ensure there is coverage, with elected officials among those calling the loss of time to be with family, in such a stressful profession, unhealthy for officers.
This kind of shuffling is not new in policing and reflects the pressure policing leaders face to respond immediately to spiking violence. But there is also tension between doing that and not draining other critical units, as evidenced last week in Chicago.
In the wake of spiking violence on the CTA, Brown announced more resources would be dedicated to the transit system. The head of the department reform office, Robert Boik, sent Brown an email, which the Tribune obtained, warning that the latest planned staffing shifts would delay critical officer training and deter progress on a court mandate to overhaul the department.
In an extraordinary move, Brown fired Boik, and has not offered further comment on why.
Stephens, the national expert, said that shifting patrols to respond to spikes in crime is one part of a larger, data-driven deployment strategy. It makes sense, he said.
But it is at these times that flexible, roving units like tactical teams or citywide teams like community safety teams need to be working at the right times in the right places.
"One of the tenets of the specialized units is they have flexible hours .. so you can deal with these spikes," Stephens said. "If you sign up for this that is what you are signing up to work different areas at different times on different problems."
The analysis done by the Crime Lab was attached to an internal Chicago Police Department email sent to Superintendent David Brown and other command staff members on March 10, 2021, according to records released to the Tribune.
The three analyses were titled "GPS Analysis by Location" and "GPS Analysis by Time of Day and Day of Week" and "Patrol Officer Counts."
Patrol officer counts included a table that showed how many patrol officers in each district responded to 15 or more calls in one month that was examined. A response was counted when an officer reported that they were answering a 911 call or other dispatched events, such as a ShotSpotter alert.
For all districts combined, the number of officers responding to 15 or more calls per month was 3,000. There are 11,500 sworn officers in the department, with most assigned to patrol.
The separate "GPS Analysis by Time of Day and Day of Week" included a 10-year review of shooting data, which examined days of the week. It showed that on weekdays, shooting incidents peak during the 9 p.m. hour. But on weekends, shooting incidents rise until 2 a.m. and then start declining.
The analysis further examined GPS data for three types of patrol responses in the so-called Tier 1 and Tier 2 districts, where most shootings happen - non-tactical district units, tactical district units and the citywide Community Safety Teams, which were launched by Brown as part of his crime-fighting strategy.
The analysis period was between June 2020 and February 2021. In all three categories, the number of officers working in the field, or on the street, appeared out of sync with the number of shootings on the weekends, according to the report.
Several charts and graphs were redacted from the 9-page report, but the written conclusions were not.
"Tactical Team field time rises throughout the day until it begins to decline during the 10 p.m. hour," the study reads. "Hours 0:00 to 4:59 a.m. of Saturday/Sunday experience 14% of the shootings but 3.8% of Tier 1 and 2 Tactical Team field time."
For non-tactical units, the field time percentage was 5.9% and for community safety teams it was 4.4%, according to the conclusions.
The Crime Lab responded to questions about how the data was collected in an email. The statement noted that GPS data is limited because it does not capture the location of officers when they leave their vehicles, perhaps for foot patrol. It also said the time period was limited to the months requested by CPD and that more analysis would need to be done to fully understand the deployment questions raised.
"We are only aware of what this data shows for the months that CPD requested to perform," the statement reads. "As a result, we do not know whether these patterns are a continuation of long-term trends or a break from the past."
National policing leaders cautioned against a rush to assume that more officers should be working in the overnight hours.
For example, there are daytime events that require a healthy complement of patrol officers to be available, including staffing large-scale events like marches or sporting events. During day shifts, police officers are often pulled out of rotation because they are in court testifying in cases, experts said.
John Eterno, a retired New York City police captain and now a professor of criminal justice at Molloy University in New York, said staffing concerns about overnight hours are not unusual.
"I would say it is something we have seen and, and I would say it is not unusual particularly in those departments that aren't efficient," said Eterno, who had not reviewed the Chicago analysis.
Eterno also said several strategies need to be used at the same time to reduce crime - ranging from gun buybacks to partnering with the federal agencies to target gun traffickers. But officer deployment is obviously critical too, he said.
"There is some connection to reducing crime when you get those officers out in the field," Eterno said. "If officers are at these locations and they are visible and doing their jobs and stopping people who are reasonably suspicious, not abusing their authority, there will be a drop in that particular area."
A third 33-page analysis that was returned to the Tribune compared the physical location of the patrol units to where shootings happen, again between June 2020 and February 2021 in the more dangerous districts.
The analysis ranked districts according to the disparity between shootings and locations of officers in the field. The Tribune was unable to fully examine the findings in the "GPS Analysis by Location" because it was nearly entirely redacted by the department.
Whether the data has been updated or used is unclear, as is whether the mayor's office ever got a copy of the reports.
Emails that were released to the Tribune show repeated requests by the mayor's office in 2021 to the police department to share the work.
On March 16, Alexander Heaton, who at the time worked a public safety policy advisor for the mayor, sent an email with the subject line "Workforce Allocation" to several department members, including Chief of Patrol Brian McDermott and Leslie Silletti, department chief of staff, asking "if Crime Lab got back to us on this."
A day later, the Crime Lab reached out to the department again.
"Mayor's office is asking for it," reads an email sent by Sean Malinowski, at the time the director of policing innovation and reform at the University of Chicago Crime Lab, to a CPD official.