The New York City Police Department on Thursday announced the arrest of a man who they say posed as a city police officer last week and sexually assaulted a Brooklyn teen.

Police Commissioner Ray Kelly said Steven Pappas, 50, seen above, is a level-three sex violator who was on parole.

Pappas is now set to be arraigned in Brooklyn criminal court on charges including a criminal sex act, sexual abuse and criminal impersonation.

On the morning of December 23 in Sunset Park, police say Pappas approached a 15-year-old boy who he spotted throwing a potato chip bag onto the ground of a subway station.

Flashing a badge and wielding a syringe, Pappas convinced the boy to enter his van, according to police, and then drove the boy to Bay Ridge, where he allegedly committed the sexual assault.

The teenager was then driven back to Sunset Park and released.

Authorities tracked Pappas down after an NYPD sergeant searching a database recognized him based on a police artist's sketch.

Pappas was arrested following a police chase.

"He was in a van. They saw him in a van, they tried to pull him over, he got away," said Kelly. "They then spotted him on the street not 15 blocks later. He did have in fact in his possession a police badge, a police shield of an active duty police officer. That's under investigation."

Police say they have also linked Pappas to another incident in February 2009, involving a 12-year-old boy who was sexually assaulted by a man who also showed a police badge on a Midtown subway platform.

Officials also say Pappas served five years in prison for a similar incident in 1999.

Pappas' last conviction was in 2009 for burglary in connection with a parking scam and he was released from jail earlier this month.