NEW YORK –  A Brooklyn police officer has pleaded guilty in a smuggling case that involved guns, cigarettes and slot machines.

Officer William Masso pleaded guilty Monday to four conspiracy counts. He could face roughly five to six years in prison when he's sentenced on June 15.

Masso was among five NYPD officers charged in October with smuggling firearms and slot machines they thought were stolen.

Authorities say they were part of a 12-person theft ring.

Three retired NYPD officers and a New Jersey correction officer were among the other defendants.

Authorities say an undercover agent paid them more than $100,000 to moonlight as gun runners while under FBI surveillance.

The arrests stemmed from an FBI-NYPD internal affairs investigation that began in 2009.