In 2011, four years after he’d joined the department, Murashea Bovell was assigned to the narcotics unit, a specialized team of the detective division comprising six to eight officers at any given time. They prowled the streets on the south side of the city in unmarked police cars, scanning for dealers and users. They wore plain clothes and conducted undercover drug buys. And they often relied on residents who, facing charges, would trade information for the hope of leniency.

At first, Bovell, then thirty-two, was eager. He especially liked the intricate work of gathering evidence for search warrants. But in just two years, he would request a transfer back to patrol because of what he’d experienced.

Since the nationwide spike in violent crime associated with the surge in crack use in the eighties, police leaders have relied on specialized squads to tally large numbers of drug and gun arrests. Though they have different names—gangs squad, anti-crime, narcotics—they operate on a similar, broken- windows logic: identify and monitor the dealers and gang members whom the police blame for the bloodshed and arrest them before they can spill more.

But with little oversight and an incentive to notch arrests, these units are susceptible to corruption. From Philadelphia to Los Angeles, communities have reckoned with the abuses of elite tactical teams. Last summer, the NYPD, by far the largest police force in the country and a bellwether for all other departments, phased out its anti-crime unit, a vestige of the department’s controversial stop-and-frisk program, which had roiled Black and Latinx communities for decades.

For its part, Mount Vernon, which borders the northern edge of the Bronx, had been on a slow decline for years. In the seventies, it was the proud center of Black culture in very white, very affluent Westchester County. Nina Simone and Betty Shabazz were neighbors. Heavy D, Pete Rock, and Sean “Diddy” Combs grew up there. But the city fell on hard times, and its law-enforcement officers responded with aggressive policing, or worse. In the nineties, the department had such a reputation for pervasive corruption that FBI agents jokingly referred to it as “Mount Vermin.”

In 1994, the feds arrested three officers for stealing $10,000 from a gym bag that the FBI had planted in an apartment. One detective was caught on camera loading the money into his vest and handing a stack to the department’s chief of detectives.