A top Boston lawyer who was working with Congressman Stephen Lynch’s US Senate campaign was buried this week, the victim of injuries suffered when he was hit by a Range Rover on Day Boulevard in South Boston on Feb. 27. William A. McDermott, Jr., who grew up in Savin Hill, was 66.

An attorney and political operative who specialized in elections laws, McDermott was the son of the late William A. McDermott, who was a longtime assistant corporation counsel for the city of Boston.

At his funeral, held at St. Margaret’s Church of Blessed Mother Teresa Parish on Monday, his son, Liam McDermott, gave the eulogy and noted that a reporter had asked him how his father got his start in politics.

“I couldn’t answer because how could this person not know where anyone in this city gets started? My dad started on the front porch, the ball field, St. Williams CYO band, the hockey rink, and community meetings,” Liam said. “You start at the bottom, you start in the trenches, you start making friends that will stand by you for life. You work hard.”

Family came first for Mr. McDermott, known to everybody as “Billy.” Along with Liam and his wife Tara, Mr. McDermott leaves a daughter, Deirdre, and her husband Auston Habershaw; a brother, John, of West Roxbury; a sister, Helen McDermott, and her partner, Kathy Meisl of Waltham; former wife Cathleen Meade; and grandchildren Maeve, Bridget, and Madelyn.

“Even during the 2004 [Democratic National Convention] —the biggest political event in four years being hosted in his home city—he opted to spend the week on the Cape at the beach with Deirdre, re-reading ‘Wuthering Heights’ during the day and watching the convention with her on TV at night,” Liam recalled.

At Mr. McDermott’s wake, there were several books on top of the casket, including former US Speaker Tip O’Neill’s “All Politics is Local” and David McCullough’s “1776.” They “summed up his life right there, the history and tradition,” said state Rep. Marty Walsh, Dorchester.

A graduate of Boston Latin School, Boston College, and Suffolk University Law School, Mr. McDermott was well known on Beacon Hill and in City Hall, where he once served as an elections commissioner during former Mayor Kevin White’s tenure. His law office was in West Roxbury.

“If anyone was in a close race, it was always, ‘Call Billy McDermott,’ ” Rep. Walsh said.

Brian Wallace, a former Democratic state representative from South Boston, remembers first meeting Mr. McDermott in a basketball game, Savin Hill versus South Boston when he was 13 and Mr. McDermott was 16. They ran into each other frequently years later, as both became involved in politics and were often on opposite sides: Wallace supported Joe Timilty for mayor, and Mr. McDermott backed Kevin White. Mr. McDermott backed David Finnegan while Wallace supported Ray Flynn.

“We always kept a strong relationship through politics and people that we knew,” said Wallace, who was one of the pallbearers on Monday.

“He just never said ‘no’ to people,” he said. “He helped people all the time. They don’t come along like that very often.”

Mr. McDermott was considered a close friend of Congressman Lynch, who is running for the US Senate seat that John Kerry left for the State Department. “For more than 30 years, Billy was a rock for me, Margaret, and countless other friends in South Boston and Dorchester and across Massachusetts,” Lynch said in a statement. “I don’t know where we’d be without the love and guidance he gave us. We are heartbroken.”

Rep. Walsh said the Dorchester community remains stunned over his death. “I think the shock still hasn’t settled into a lot of people,” he added.

Jim Hunt, Jr. was coming out of the Ward 16 Democratic Committee’s caucus at the McKeon Post last Wednesday night into blinding rain and heavy winds when the e-mails and phone calls started to come in.

He called Mr. McDermott a confidant whom he had known for 40 years. “I think we’ve lost one of the brightest political minds of our time, someone who could be extremely sympathetic and someone who could be very direct and analytic,” he said.

Hunt recalled that he was considering running for the State House decades ago, and Mr. McDermott told him that he needed a lawyer. Hunt recalled telling him he didn’t have any money, prompting Mr. McDermott to respond, “Who said anything about money? This’ll be fun.”

Suffolk District Attorney Daniel Conley’s office said State Police detectives were investigating a “fatal collision” on Day Boulevard near L St. on Feb. 27. State Police arrived at the scene at 7:30 p.m., after a 33-year-old South Boston resident who was operating a 2012 Range Rover called 911. The caller, who stayed at the scene, “did not show signs of intoxication,” Jake Wark, a Conley spokesman, said in an e-mail to reporters, adding that no charges have been brought but interviews are “ongoing” and a probe is “very active.”