Officer Brendan Sullivan first used the breathy voice of a seductive woman. Then he panted.

Then came the animal noises.

Paul Vogel, a 52-year-old Brooklyn man, was the recipient of the menagerie of voice mail messages. For years, he had been frustrated at police cruisers and Fire Department vehicles parked on the sidewalk and in crosswalks in his Prospect Heights neighborhood, which drove him to call the city’s 311 complaint line hundreds of times. Officer Sullivan retaliated, calling him and leaving voice mail messages for 10 months, according to city records.

On May 16, 2021, the officer used his department-issued phone and left a voice mail of dolphin noises, according to the records. Nine days later, he escalated the harassment, adding seal barks and the bleating of sheep.

The six messages that Officer Sullivan left between March 2, 2021, and Jan. 24, 2022, came to light after the city’s Department of Investigation began looking into retaliation by the police against people who had complained about illegal parking. Streetsblog, an online news organization, had been publishing stories about the allegations, including one that quoted Mr. Vogel.

Last month, Officer Sullivan agreed to pay the price: a $500 fine to the city’s Conflicts of Interest Board, which concluded in a disposition that Officer Sullivan had “sought to discourage a citizen from exercising his constitutional right about government action.” He also had to give up 60 days of annual leave, which is worth about $25,000 in pay.

The officer, who joined the force in 2007 and was posted to the 77th Precinct, “should be held to a high standard of compliance with the conflicts of interest law,” according to the disposition issued by the board.

He also had to attest to his misdeeds in a sheepish first person: “I left a voice mail for him in which I pretended to be a former romantic partner,” Officer Sullivan acknowledged.

Mr. Vogel said Tuesday that the punishment felt “pretty significant for what are ultimately some prank calls.”

“On the other hand, the guy is a cop and he harassed a civilian,” he said. “The idea that someone who would do that in their official capacity still has a badge and a gun doesn’t make me feel very great.”

Officer Sullivan was placed on modified duty, which means he is not patrolling, the police said. He could not be reached for comment, nor did his lawyer respond to messages.

“The department is dedicated to ensuring pedestrian safety for all New Yorkers,” the police said in a statement.

For years, residents throughout the city have complained about illegally parked cruisers and emergency vehicles, posting photos of offenders on social media and pointing out the problem to City Council members and at precinct meetings. The complaints became so frequent that this year, the office of the U.S. attorney for the Southern District of New York sent a letter to the city, threatening a lawsuit if officials did not put a stop to the practice.

The police said Tuesday that the department was “working internally to review and address the concerns raised in the letter.”

The first, on March 2, 2021, claimed to be from an ex, who, in a whispery voice, told Mr. Vogel, “I hope you still dream about me.”

“Just want to let you know that I miss you,” the voice said, calling him “Paulie Vee.” “I hope you pick up my call next time. You’re still the best I ever had.”

The second voice mail featured heavy breathing.

The messages did not stop at the animal sounds. Officer Sullivan called back two more times, saying “Paul, pick up” and “Paulie, answer my calls.”

The Brooklyn district attorney’s office previously investigated the case and determined that there was no criminality.

It was not clear how the Department of Investigation traced the voice mail messages to the officer. The city’s Civilian Complaint Review Board, an independent oversight agency, found he had engaged in sexual misconduct by sending the harassing messages, had abused his authority and was untruthful with investigators when he denied leaving the messages. The board recommended the loss of 60 days of leave and on Sept. 11, Edward Caban, then the police commissioner, approved the discipline.

John Kaehny, who pushed for the 311 system and is now executive director of the watchdog group Reinvent Albany, said using information derived from a 311 call to harass a resident could have a “chilling” effect.

“This is an abuse of power,” he said. “And it wrecks the efficacy of 311, which remains and is the most important accountability tool, short of voting, that people have.”

In a statement, the city’s Office of Technology and Innovation, which runs the system, said that “protecting the public trust and integrity of the millions of NYC311 calls received annually is a priority.”

“Any conduct inconsistent with the city’s 311 privacy policy is handled accordingly,” the statement said.

The 311 service “only collects identifying information needed to work on your service request,” which is supposed to be shared only with “city agencies, city workers and vendors,” according to the system’s website.

The system “fully cooperates with law enforcement agencies in identifying those who may access services for illegal activities,” according to the website.

Mr. Vogel said he would not be deterred from calling again.