John Lynch, a longtime Boston City Hall employee, was sentenced to 40 months in prison on Friday after pleading guilty last year to accepting a bribe of $50,000.

Lynch pleaded guilty to one count of bribery. According to the charges against him, filed last August, Lynch accepted a bribe of $50,000 from a real estate developer. In exchange, Lynch agreed to try to sway the vote of an unnamed member of Boston's Zoning Board of Appeal in favor of one of the developer's projects.

Lynch, 67, was working as assistant director of real estate for the Boston Redevelopment and Planning Agency at the time of the crime. He worked for the city's Department of Neighborhood Development for 20 years before that.

Charging documents did not name the developer or the ZBA member.

It's not clear that Lynch did attempt to influence the ZBA member, or that any member of the ZBA was aware of the criminal plot. An independent audit of the ZBA commissioned by Mayor Marty Walsh, released last fall, did not find evidence of wrongdoing or knowledge of any criminal enterprise on the part of any "current" ZBA member. But the report also noted that federal investigators were reviewing records tied to one former ZBA member, Craig Galvin.

WGBH News reported in September that Galvin, a real estate agent and founder of the Galvin Group real estate firm, brokered the sale of multiple properties for which he had voted to approve zoning relief while serving on the ZBA. Galvin has not been accused of any wrongdoing.

In the sentencing hearing Friday, Lynch's attorney, Hank Brennan, told U.S. District Judge Patti Saris that Lynch was remorseful for his actions, took responsibility for his crime, and understood that he had committed a serious violation of the public's trust.

Citing dozens of letters of support from neighbors, Lynch's church and charities with which he'd been involved, Brennan asked Saris not to include prison time in Lynch's sentence.

"Mr. Lynch did not go to trial," Brennan told the judge. "When he was confronted, he embraced responsibility as quickly as probably anybody could. ... He fully admitted everything he had done. He accepted his punishment."

U.S. Assistant District Attorney Dustin Chao acknowledged that the many letters of support for Lynch showed a man who had done much good over his four decades in public service.

The letters, Chao said, showed "a man who was a leader, a man who was a helper, a man who could get things done."

But Lynch's crime "wasn't committed in an instant," Chao argued, pointing to Lynch's admission of receiving the bribe in several payments. "Mr. Lynch took bribe payment after bribe payment."

Before his sentencing, Lynch briefly addressed Judge Saris, standing to say he was sorry for his crime.

"I'd like to apologize to the court for using its valuable time," Lynch said. "I certainly apologize to my family for the embarrassment and shame I brought upon them, and to the citizens of Boston, whose trust in me I abused."

In handing down the 40-month sentence, along with one year of supervised release, Saris acknowledged Lynch's long record of public service and charitable work, his strong family values, and said she believed Lynch was sincerely remorseful and that he would never make the same mistake again.

But, Saris said, crimes of corruption cannot be taken lightly.

"Corruption by public officials breeds disrespect for government and also undermines our civic values," Saris said. "It should be clear to every public official that if you take a bribe, you should expect to go to jail."