As the head of the Nassau police’s intelligence gathering operation, Patrick Ryder successfully pushed to overhaul the department’s crime-mapping — an effort widely credited with driving historic crime reductions in the county.

Ryder, who besides his statistical prowess has a reputation as a hard-charging investigator, was named acting commissioner effective next month with the retirement of acting Police Commissioner Thomas Krumpter, officials said Monday.

Ryder, 54, who until January was a detective sergeant overseeing intelligence and the department’s robust asset forfeiture operation, declined a Newsday interview Monday.

But in a statement, the deputy commissioner called the department “one of the most educated and well respected service-orientated police departments in the country” and called his promotion the “highest honor.”

County Executive Edward Mangano said in a statement that he chose Ryder to take the helm of the department because of his work on intelligence-led policing models and assistance in procuring funds for technology.

“With special units becoming ever-demanding due to global terror threats, Acting Commissioner Ryder will continue to pave the way for a bolstered police force that includes 150 additional police officers, 911 operators, Ambulance Medical Technicians and the formation of special units,” Mangano said.

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Mangano spokesman Brian Nevin did not respond to questions about whether Mangano planned to leave Ryder as acting commissioner until after the November election or commence a search for a new commissioner.

It was just last year that Ryder investigated a sexting scandal, which turned out to be a hoax, involving Mangano and a county contractor.

Ryder famously told a room full of reporters at a news conference announcing the results of his investigation that he personally told Mangano that if he lied to him, “I will be the guy that walks in and puts the handcuffs on you, no problem.”

Mangano was later indicted on federal corruption charges, to which he has pleaded not guilty.

Ryder, who began his law enforcement career with the NYPD, where he worked for about two years patrolling Bedford-Stuyvesant, Brooklyn, in the 1980s, entered the Nassau police academy in 1986.

Highly decorated, Ryder has won multiple medals of commendation, the department’s highest award and a slew of other awards. In a 10-month tour with a narcotics team, he made 200 arrests.

But his career hit a roadblock in 1990, when he was accused of beating a handcuffed suspect outside a Merrick bar. A Nassau judge later threw out the indictment, and a second grand jury declined to indict him. At a court appearance in the case, his fellow officers crowded into the courthouse to support him.

James McDermott, head of the Nassau Police Benevolent Association, said he was hopeful the union could have a good relationship with Ryder.

“He’s a cop’s cop, and I consider him a friend,” said McDermott, adding that he and Ryder worked together as rookies in the NYPD and later in Nassau’s Elmont-based Fifth Precinct. “But he’s management and I’m union, so hopefully we can find a middle ground and I believe we will — for the police officers’ interests and the interest of the public we serve.”

Ryder hasn’t changed from his early days on the force, even as he has climbed the ranks, McDermott said. He described the next commissioner in this way: “Type A personality, hard worker, nonstop, crazy energy. He was a very active cop.”

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McDermott said Ryder “always understood the gray area that exists in the world. He’s not a cookie-cutter guy. He’s somebody that you can speak with and he can see your side of the issue. He’s not gonna give away the store. But he is reasonable. And I hope that continues.”