NYPD brass have put three precincts under the microscope because of a continuing drop in quality-of-life enforcement at a time when homicides and shootings within their boundaries have sharply risen.

Chief of Department James O'Neill said last week that since cops had a slowdown in arrests since the killings of officers Wenjian Liu and Rafael Ramos, he and his staff have been looking at each precinct. They noticed three -- in north Brooklyn and the Bronx -- that also experienced a rise in shootings and homicides.

O'Neill wouldn't say whether the slowdown in quality-of-life activity directly correlated with the increased violence and wouldn't identify the precincts, although six seem to be among a short list of possibilities.

O'Neill said he had called in the commanders recently to take a "real hard" look at the computer statistics on their activity levels. Commissioner William Bratton indicated he wanted to see the arrest activity increase.

"There are still certain precincts we are looking at closely," Bratton said during a briefing with reporters a week ago. "If they are not back in the game yet, we will find ways to get them back in the game."

Since arrests, including those for quality-of-life issues, dipped precipitously in December, cops have been picking up their activity on the street.

Officials admitted that officers had been in a slowdown, in part because of the need to deal with the many demonstrations that followed the decision by a Staten Island grand jury not to indict any cops in the death of Eric Garner.

The slowdown was also attributed to cops doubling up on patrols and watching their backs as a security precaution after the Dec. 20 killing of Liu and Ramos.

Arrests are still down by about 24 percent from the same period last year, according to police data, a level Bratton said was "pretty close back to normal-normal behavior." He noted that some of the decline was attributable to the city decision not to arrest people for possession of small amounts of marijuana.

But since Jan. 1, the city has also seen an increase in shootings and homicides. Through Feb. 1, homicides were up 18 percent, from 33 to 39, while all arrests were down 24.6 percent, from 7,513 to 5,668, police statistics showed.

Drilling down into the data, six precincts showed an increase in shootings and homicides along with sharp decreases in criminal summonses usually associated with quality-of-life offenses. Those precincts were the 81st, 90th and 77th in north Brooklyn, and the 40th, 44th and 46th precincts in the Bronx.

An NYPD spokesman wouldn't identify the particular precincts O'Neill was scrutinizing.