What makes a city ruined by crime if its most effective strategy against armed violence has also fueled accusations of abuse and corruption?
The answer, in Baltimore, is to try again ─ but this time, with more care.
Frustrated by the city's stubbornly high homicide rate ─ including a record setting of 2017 ─ Mayor Catherine Pugh fired her police commissioner on Friday and replaced him with a Baltimore policeman who promised to expand the previous efforts of " police surveillance ".  Rates of killings per 100,000 people last year in selected cities ” title=””/>
Baltimore, along with many other US cities, has a complicated relationship with tactics, that involves flooding-crime neighborhoods with officers who focus on the most violent or chronic offenders. It has been shown to curb armed violence, but at a high price.
The Baltimore version of the hot spots police has forced the city to reach costly settlements with people claiming violations of their civil rights, as documented by The Baltimore Sun. One unit, called the Gunfight Task Force, turned out to be corrupt. And a detective who planned to testify against members of that unit was shot dead in November. That case remains unsolved.
Related: Baltimore Detective Sean Suiter dead one day before testimony in case of police corruption
But in his new emphasis on police surveillance, Baltimore is being watched by the federal government. The police department, under threat of a civil rights complaint by the Department of Justice, promised to change the way it operates, as a result of an investigation that began with the death of Freddie Gray in April 2015 for injuries suffered while he was in police custody. The death of Gray unleashed riots in the city, which were followed by a federal investigation documenting a pattern of unconstitutional arrests and searches that eroded trust in neighborhoods suffering the worst violence.
After consulting with the Department of Justice, Pugh said he hired a modern-day police guru: Sean Malinowski, a Los Angeles Police Department Commander who advises cities on high-tech policing techniques, including the use of "nerve centers" based on equipped precincts with software that helps officers predict where the shots will occur. That approach has been credited with the long-term fall of the Los Angeles crimes and the recent crime reductions in some of Chicago's troubled neighborhoods.
This strategy is a modern iteration of the hot-spot policy type that became popular during the 1980s, with officers plotting crimes with pins on maps, and expanded in the 1990s and 2000s with computerized crime analysis programs Compstat. With advances in technology came the use of predictive surveillance software. Current versions, including those by Malinowski, are based on the rapid analysis of criminal data, along with the use of surveillance cameras and sensors that alert the police to the sound of the shots and the downloading of that information to the telephones. smart of the officers.
Related: Trump's objections do not stop the Baltimore police review after the death of Freddie Gray
Bill Bratton, the former police commissioner in New York ─ where he presented the Compstat in 1994 ─ and Los Angeles ─ where he had Malinowski develop predictive surveillance programs ─ he said in an interview that the latest version was "Compstat on esteroids".
"We have advanced to the point where we are using algorithms to identify where, when and with much more precision," Bratton said.
The history of the police hot spots ─ a consequence of the philosophy of "broken windows" of the police that led to the techniques of stop and search ─ is also a story of the dangers of the aggressive application of the street . Several of the largest cities in the United States, including New York, Los Angeles and Chicago, have used tactics that have been declared unconstitutional for disproportionately attacking minorities. That has sown enmity in black and Latino communities.
Police leading new iterations of hot spot surveillance emphasize the importance of maintaining community trust. In fact, some say that the modern version reduces the total number of police interactions with people on the street.
Related: Baltimore Police Commissioner Kevin Davis was replaced by mayor in the middle of a record homicide rate
Bratton compared the application of the hot spots police with a doctor attending a patient.
"Police and police strategies are like medicines ─ you should know how much to apply and when to apply, otherwise you will have an overdose," he said.
In the case of Baltimore, it has been shown that the monitoring of conflict points curbs violence with firearms. A study by the Johns Hopkins Center for Gun Policy and Research released last week concluded that special units focusing on violence and firearms in high crime areas suppressed the number of shots. But the researchers also noticed that many of the units performing these tasks encountered legal problems.
"Without sufficient professionalism, oversight and accountability, these units can cause serious harm to people in the communities they are supposed to protect and the reputation of the department, which undermines its long-term effectiveness," the researchers wrote.
DeSousa, who served as assistant commissioner under his predecessor, Kevin Davis, balanced the harsh conversation for criminals with the promise to take into account civil rights issues.
"I have a very strong message for the triggers: we are pursuing them," DeSousa said at a press conference on Friday. "It's going to accelerate, the district commanders of the nine districts know who they are and we're pursuing them, and I want everyone to know that it will be done in a constitutional way."
Andrew Ferguson, who studies predictive policing at the David A. Clarke School of Law at the University of the District of Columbia, said he thinks very highly of Malinowski and his approach to hot-spots policing. But their success will depend on whether Baltimore can do whatever it takes to make it work.
"Are they going to invest resources in that? They spent real money on L.A. and Chicago," Ferguson said.
The Baltimore Police Department did not respond to requests for details about the DeSousa plan.