New York City Police Commissioner William Bratton acknowledged Friday that his officers participated in a work slowdown since the fatal shootings of two NYPD officers late last month, but he said that cops are “beginning to return to normal patterns of work,” NPR reported. Parking summonses have been down drastically since the Dec. 20 deaths of Officers Wenjian Liu and Rafael Ramos, which led to increased tensions between the NYPD and Mayor Bill de Blasio, whom the city’s police unions accused of fueling anti-police sentiment that led to the officers’ killings.

 “We quite clearly were in a slowdown,” Bratton said. “It is being corrected … we've been taking management initiatives to identify where it's occurring, when it's occurring. I think the officers themselves have, on their own, been beginning to return to normal patterns of work. So we're coming out of what was a pretty widespread stoppage of certain types of activity.”

Since Liu and Ramos were shot and killed by Ismaaiyl Brinsley, parking summonses issued by the NYPD have dropped 93 percent from the same period last year, according to the New York Post. The lax enforcement cost New York City $10 million per week, the paper reported.

Patrick Lynch, head of the Patrolmen’s Benevloent Association, one of New York City’s police unions, denied that there was an NYPD slowdown, saying that the plunge in minor arrests and summonses was due to increased patrols after Liu and Ramos were killed, according to NPR.

Bratton said the increased enforcement doesn’t account for the drop in summonses and arrests. “That would be one factor in terms of the decline of some of the numbers, but it would in no way influence significantly the overall drop-off of activity,” he told NPR.

NYPD officers have accused de Blasio of fomenting anger against police by not cracking down on the protests supporting Eric Garner, the unarmed black man who died after being put in a chokehold by a white cop, and for saying that he told his half-black son, Dante, to be wary of interactions with police. Cops have expressed their displeasure with de Blasio by turning their backs to him when he spoke at a Brooklyn hospital shortly after the deaths of Liu and Ramos and at Ramos’ funeral.