During the first presidential debate Monday night, Donald Trump and Hillary Clinton sparred over the use of stop-and-frisk as a means to reduce murder rates in Chicago – and it didn’t take long for the NYPD to chime in on social media either.

“We have to bring back law and order,” Trump said. “Now whether or not, in a place like Chicago, you do stop-and-frisk, which worked very well. Mayor Giuliani is here, it worked very well in New York. It brought the crime rate way down …”

Clinton, however, was quick to point out that stop-and-frisk in New York was ruled unconstitutional.

“Stop-and-frisk was found to be unconstitutional, and in part, because it was ineffective,” Clinton said. “It did not do what it needed to do.”

In fact, NYPD Assistant Commissioner for Communication & Public Information J. Peter Donald took to Twitter during the debate to help with some fact checking.

“Stop question & frisk has decreased nearly 97% in NYC since '11. Crime, murder, & shootings have decreased significantly during same period,” Donald tweeted.

“Critics decried that having fewer stops in ‪#NYC would result in higher crime. The very opposite occurred,” he continued in a second tweet.

Trump argued that the only reason the controversial policy was ruled unconstitutional was because Mayor Bill de Blasio, a staunch opponent of stop-and-frisk, declined to follow up on an appeal of the ruling.