New York City – from www.nydailynews.com – It’s the mother of all internal affairs.

The NYPD’s Internal Affairs Bureau launched a massive, year-long investigation to prove Deputy Inspector Valentim Neves [pictured] lied under oath about having sex romps with an underling.

What it found was eye-popping: Neves and Officer Mareli Hnatko were found to have had sex in his office, a department vehicle and hotels in New Jersey.

There were “well in excess of 100” hookups, the IAB report says.

So many, that Neves, 53, later told investigators he couldn’t even begin to give them a number.

The sex cops went into action after Neves’ wife, a retired NYPD sergeant, dropped a dime on him to IAB in January 2009 after the two had a fight.

She reported that he was having a “personal” relationship with Hnatko, 41, who worked for him in the NYPD’s School Safety Division. Neves had denied he was sleeping around when it came out in a separate suit that charged he was treating other women under him unfairly.

With his wife’s words against him, the IAB’s special investigations unit pounced. They used video cameras, subpoenaed hotels and motels in New Jersey and Queens, and reviewed cell phone, E-ZPass and roll call records.

A sergeant and detective were tailing Neves on Dec. 28 when they observed him hand Hnatko a plastic bag.

She later admitted the bag contained a Christmas present from him – a Tiffany necklace with key pendant.

The probe found “sexual conduct both on and off duty, in and out of department facilities, including vehicles,” an IAB memo said. Both are facing dismissal from the force for fraternization and false statements.

Hnatko is not being sued. She declined comment but told IAB investigators she and Neves bonded as they talked about their troubled marriages and because they each have special-needs children.

NYPD spokesman Paul Browne said there was nothing unusual about the breadth of the probe.

“IAB employed standard investigative techniques in investigating misconduct allegations,” Browne said.

The affair was first alleged in a federal suit filed by Officer Robin Marable that complained Neves discriminated against female cops while lavishing Hnatko with overtime and special treatment.

Marable’s lawyer, Eric Sanders, said the probe may have proved Neves slept around, but IAB dropped the ball concerning other allegations from his wife, including one that he prepared taxes for high-ranking NYPD officials who protected him through the years.

“I don’t care about [Neves’] sex life,” said Sanders of the Law Firm of Jeffery Goldberg in Lake Success. “This case is about corruption and the Police Department is throwing him to the wolves to cover up who he was doing business with.”

Confronted at a humiliating IAB interview in January, Neves who is also a lawyer, laid bare his fears:

“I am in a bad situation,” he told Deputy Inspector David Grossi. “I have 30years on the job. …What I did were make mistakes that were emotionally driven.”

“I don’t want my career to be defined by a lapse in judgment on my part. … I’m nervous. I’m scared. The whole situation is embarrassing.”