Chicago police are shooting fewer residents and drawing fewer civilian complaints than they were before protests over the fatal 2014 shooting of a black teenager, Laquan McDonald, by a white police officer.

The decline in shootings and complaints coincides with an apparent change in police behavior over the same period. Chicago police appear to have become less proactive and aggressive in the wake of the protests, a pattern that we have also identified in other cities that have experienced high-profile deaths of black men involving police officers. In at least three cities, including Chicago, the apparent pullback in policing was accompanied by a sharp increase in gun violence.

It is possible that the scrutiny that followed the McDonald shooting has made Chicago police more passive — less likely to stop suspicious people, for example, and more cautious in investigating reported crimes — leading to both the rise in gun violence and the decline in police shootings and complaints. But the Chicago Police Department offers another theory: that increased training has helped police officers do their jobs without drawing complaints or resorting to lethal force.

In October 2014, police officer Jason Van Dyke shot McDonald 16 times, sparking protests and drawing widespread scrutiny to the Chicago Police Department more generally. Protests intensified last fall as activists demanded the release of a dashboard-camera video showing the shooting; in November, the city released the video on a judge’s orders. (In December, Van Dyke was indicted on six counts of first-degree murder. He has pleaded not guilty.) The U.S. Justice Department launched an investigation into the police department, and Chicago Mayor Rahm Emanuel fired the police chief and created the Chicago Police Accountability Task Force, which in an April report cited residents’ reports of officers’ “overaggressive and hostile demeanor” in some situations.

In April, we found that Chicago police made far fewer arrests, especially for gun- and drug-related crimes, in the months following the release of the McDonald video. Now data collected by the Invisible Institute, a Chicago nonprofit that promotes police transparency, shows that the department’s apparently less aggressive posture has also coincided with a drop in both police shootings and civilian complaints against officers. Both measures were lower early this year than they’d been at almost any time since at least 2012. (Chicago Police Department spokesman Anthony Guglielmi said he was “not going to deny” that increased scrutiny on police behavior nationally “has an impact on officers.” But officers haven’t abandoned proactive policing, he said.)

Civilians can file complaints against the Chicago police for a wide variety of offenses, ranging from verbal abuse to physical brutality. The department keeps records on all complaints, whether substantiated by investigation or not; the Invisible Institute obtained those records back to April 2012 via an open records request. Using that data, we tallied the 30-day rolling average number of complaints from May 2012 to April 2016, the most recent data available.

Complaint counts have been declining since 2012, but starting in mid-November 2015 — about two weeks before the video was released — complaints against police dropped at a rapid rate. That decline came during a period of intense scrutiny on Chicago’s police, culminating in state Attorney General Lisa Madigan’s Nov. 18 order that the McDonald video be released publicly. (The video came out on Nov. 24.) A previous large decrease occurred after the Oct. 20, 2014, shooting of McDonald, a year before the video was released to the public. The 30-day average rate of complaints fell more than 50 percent from its peak in 2013 to April 2016.

Police shootings have shown a similar decline. According to data that the Invisible Institute scraped from the website of Chicago’s Independent Police Review Authority, the annual rate of police shootings fell after the McDonald shooting and dropped again during the period of scrutiny leading up to the release of the video. (Shootings also fell after the March 2012 shooting death of 22-year-old Rekia Boyd by an off-duty police officer but subsequently rose again.) From the month in which the McDonald video was released through April of this year, the annual rate of shootings has remained lower than at any other point in our data, which goes back to September 2007. There have been four months since McDonald’s shooting in which there were no police shootings, something that occurred only twice in the seven years before the shooting.

There is no way to be sure what was behind the drop in complaints or shootings. But the declines coincided with an apparent shift in police behavior. Not only have overall arrests fallen, but there was a particularly significant decline in the number of narcotics-related arrests, which are a rough proxy for “proactive policing.” At the same time, stop-and-frisk-type contacts have fallen significantly in 2016; through Oct. 2, the number of such contacts had fallen by 82 percent compared with the same period in the previous year, according to police department data. Taken together, the evidence suggests a police force that has become less proactive and aggressive.

It is possible that the apparent decline in police activity is directly causing the decline in complaints and police shootings. After all, fewer encounters between civilians and police produce fewer opportunities for complaints or for a situation to turn violent. Police complaints fell nearly in sync with narcotics arrests after the McDonald tape was released. Complaints and narcotics arrests fell 30 percent and 39 percent, respectively, between October 2015 and February 2016.

Guglielmi, the police department spokesman, offered a somewhat different explanation. He credited the decline in shootings and complaints to better training implemented by the department in the past few years, including “procedural justice and police legitimacy efforts,” which are designed to improve community relations and make policing more fair. He pointed to the longer-term decline over the last several years — before the release of the McDonald video — as evidence that the trend isn’t the result of reduced policing in the wake of the protests. “CPD officers continue to do the most dangerous work of all and that’s engage gun offenders who drive the majority of our city’s violence,” Guglielmi said. “Every one of those instances could instantly lead to an armed confrontation, and we are seeing officers do more of this dangerous work than we even saw last year.”

Rajiv Sinclair of the Invisible Institute said increased scrutiny on police behavior, including a “dramatic increase in filming,” could be making officers more reluctant to engage with the public but also more deliberate when they do so. He cautioned against any single explanation for the decline: “There are a lot of factors.”

The Chicago police have continued to be less active in recent months. Narcotics arrests for the period from Jan. 1 through Oct. 3 were down 47 percent this year, compared with the same time frame in 2015. Meanwhile, crime — especially gun violence — has remained high. The total number of murders, which began increasing after the release of the video, is up by 44 percent so far this year after a 16 percent jump in 2015. Chicago is currently on pace for its highest murder total since the late 1990s and will likely experience its biggest one-year jump since the FBI began keeping track in the early 1930s.

Relatively few of the city’s murders are solved: As of Oct. 3, the Chicago Police Department had cleared only 21.0 percent of murders and other homicides and 2.6 percent of nonfatal shooting incidents in 2016. That’s down considerably from 2015, when 31.8 percent of homicides and 6.1 percent of nonfatal shootings were cleared.

The Chicago Police Department has made significant strides in reducing negative interactions between police and civilians, as measured by complaints and shooting incidents. But those strides may have come at the cost of a severe drop in arrests and a worsening wave of violent crime.

Jeff Asher contributed research.