Gilberto Mercedes, 42, a 14-year veteran of the force who works out of the 48th Precinct in the Bronx, was nabbed about 4:45 p.m. Friday after he was caught with “a quantity” of marijuana inside a Knickerbocker Ave. liquor store in Bushwick, officials said.

Investigators found Mercedes moonlighting behind the counter of the Neighborhood Liquor Store near Cornelia St. when they charged him with criminal sale of marijuana and unlawful possession of marijuana.

He was also charged with endangering the welfare of a child for allegedly buying alcohol for a minor, and criminal possession of a weapon when a firearm with its serial number scratched off was found behind the counter, officials said.

Dressed in a green hoodie and blue jeans at his arraignment Saturday evening in Brooklyn Criminal Court, the troubled cop shamelessly blew a kiss at his girlfriend.

A judge ordered him held on $10,000 bail.

“He’s not guilty all across the board. He was in the wrong place at the wrong time,” defense attorney Patrick Brackley said, adding that Mercedes had no idea the firearm was hidden behind the counter.

“It was not his weapon and he had no knowledge of its presence,” he said.

Prosecutors said the NYPD Internal Affairs Bureau had been investigating Mercedes over his marijuana sales.

Mercedes’ girlfriend and sister, who watched from the courtroom gallery, refused to comment about the arrest.

A law enforcement source said Mercedes had been in trouble with the department before, and was disciplined after he was accused of stealing department property several years ago.