Mario Biaggi, a celebrated New York City police officer who served for two decades as a Democrat in the U.S. House of Representatives before resigning in 1988 after federal corruption convictions, died June 24 at his home in Riverdale, N.Y. He was 97.

A granddaughter, Alessandra Biaggi, confirmed his death but did not cite a specific cause. Mr. Biaggi reportedly suffered from colon cancer in recent years. For decades, he had used a cane, crutches and, at times, a wheelchair, the consequence of a confrontation with a runaway horse in the line of police duty in 1946.

A son of Italian immigrants, Mr. Biaggi grew up in a New York City tenement and served 23 years with the New York Police Department. He received nearly two dozen citations — reportedly one of the highest tallies in the department’s history — and was sometimes described as the most decorated police officer in the United States.

A pair of the awards recognized his actions during confrontations in which he fatally shot two men, one of them a suspect who tried to attack him with an ice pick.

Mr. Biaggi’s law-and-order bona fides helped propel his political career, and in 1968, he won a vacant seat in a House district covering a portion of the Bronx. His legislative accomplishments included winning passage of a ban on the armor-piercing ammunition known as “cop killer” bullets and helping establish the National Law Enforcement Officers Memorial in Washington.

Mr. Biaggi on the Capitol steps in Washington in 1981. (James K. W. Atherton/The Washington Post)

But he was, by his definition, “famous for being a service congressman.”

“He would pick up and make the phone call, and when he did, it was like God himself was making the call,” John Dearie, a former New York assemblyman and fellow Bronx Democrat, once told the New York Times. “He would do it for the son who needed to get his mother a bed in a nursing home, or the family who needed to resolve a Social Security problem, or the kid who needed help getting a job application at the Parks Department.”

Constituent services helped Mr. Biaggi amass the political power base from which he won nine congressional reelection races.

He mounted a bid for New York City mayor in 1973, but the campaign failed after questions arose about his testimony in earlier grand jury proceedings about his financial dealings and other matters. Mr. Biaggi had invoked the Fifth Amendment. (City Comptroller Abraham D. Beame, a Democrat, won the election.)

Mr. Biaggi’s most serious ethics investigations were aired during two federal criminal trials in the late 1980s. In one case, he was charged with illegally accepting a Florida trip from Meade H. Esposito, one of the city’s Democratic power brokers, in exchange for his efforts to accelerate federal contracts with a Brooklyn ship-repair company.

In a wiretapped phone conversation released during the proceedings, Esposito was heard telling Mr. Biaggi that the trip is “not a gift. It’s uh, it’s a, uh, manifestation of my love for you.”

“You didn’t give it to me because I’m a member, member of Congress,” Mr. Biaggi replied, according to a transcript published by the New York Times.

“Nah. Never. . . . No way,” said Esposito.

In 1987, the two men were convicted on charges related to the offer and receipt of an illegal gratuity but were acquitted of the more severe offences of bribery and conspiracy. Mr. Biaggi also was found guilty of obstruction of justice. He was sentenced to 30 months in prison, fined $500,000 and, separately, barred from voting in the House.

In the other case, Mr. Biaggi was accused of extorting stock payments in exchange for political favors on behalf of Wedtech, a once small tool-and-die shop in the Bronx that became a massive military contractor. A prosecutor was U.S. Attorney Rudolph W. Giuliani, the future Republican New York mayor and presidential candidate.

Co-defendants in the matter included Mr. Biaggi’s son Richard Biaggi; a former law partner, Bernard G. Ehrlich; and Stanley Simon, a former Bronx borough president. In his defense, Mr. Biaggi argued that the payments were made in exchange for legal services and argued that Wedtech scarcely needed his help, given the firm’s close ties to Reagan administration officials.

In 1988, Mr. Biaggi was convicted of 15 felony counts brought against him, including counts of racketeering, conspiracy and extortion. Mr. Biaggi’s son, Ehrlich and Simon were convicted on related charges.

Mr. Biaggi resigned his congressional seat after the conviction. He was sentenced to eight years in prison in the Wedtech case and was fined $242,000. He served 26 months before he was released for reasons of poor health.

He sought to reclaim a congressional seat in the 1992 election. “I paid my debt to society,” Mr. Biaggi told the Times, “a debt that I maintain I didn’t owe.” He lost in the primary to Rep. Eliot L. Engel (D-N.Y.), who had replaced Mr. Biaggi after his resignation in 1988 and who remains in office today.

Mario Biaggi was born in New York City on Oct. 26, 1917. His father was a marble worker, and his mother was a charwoman. Mr. Biaggi shined shoes, delivered laundry and carried the mail, the Times reported early in his political career, before joining the police department in 1942.

The dean of New York Law School, after hearing Mr. Biaggi speak at a public event, offered him a scholarship despite his lack of previous university education. He received a law degree in 1963 and later practiced with the New York firm of Biaggi, Ehrlich and Lang.

His wife of 57 years, the former Marie Wassil, died in 1997. Survivors include four children, Richard Mario Biaggi of Pelham Manor, N.Y., Mario Biaggi Jr. of Eastchester, N.Y., Barbara Biaggi of New Rochelle, N.Y., and Jacqueline Biaggi of Riverdale; 11 grandchildren; and four great-grandchildren.