According to Bill Vanderool, writing in the American Rifleman magazine in October 2010, Walsh's 100th birthday party involved his family serving him three cakes, marking three key elements of his life. The first had the seal of the Federal Bureau of Investigation (FBI); the second that of the United States Marine Corps; the third bore the five Olympic rings.
By the time Walsh experienced his first Olympics - at which he finished 12th in the 50 metres free pistol event - he was already 41, with a war record of conspicuous gallantry as a lieutenant colonel in the First Marine Division.
Before that, however, he was one of the first "G-men" (slang for Government men) with the FBI, which he joined in 1934 having graduated from Rutgers Law School.
According to a piece which appeared on the USA Shooting site to mark his 106th birthday on May 4 last year, Walsh was soon involved in tracking down many of the notorious crime figures of that age. As a 27-year-old rookie agent he discovered the body of Chicago gangster Baby Face Nelson after a shoot-out which had left two FBI agents dead.
A year later he helped to bring to justice Arthur "Doc" Barker of the infamous Barker Gang. Barker complained about being arrested by a "damn baby-faced kid". Later on the same day, Walsh shot and killed gangster Rusty Gibson.
In 1937, Walsh came close to being killed himself as he was working undercover as a salesman in a sporting goods store in Bangor, Maine to help bring down another criminal band - the Brady gang. In a shoot-out he took bullets to the chest and right hand before shooting gangsters James Dalhover and gang leader Al Brady.
Interviewed later about his FBI career, Walsh responded: "I thought to myself, this might be a good outfit to tie up with. I am not trying to pin medals on myself but the people in the FBI knew that I was very handy with firearms."
Those skills had been laid down when, as small child, he had begun shooting pegs off his aunt's clothesline with a BB gun which he exchanged at the age of 12 for a .22 calibre rifle which he used to shoot at rats in the city dump.
The firearm he used at the 1948 Olympics was uncommon in the United States at the time. Speaking to the highly respected US sports journalist Alan Abrahamson in 2011, Walsh recalled that during his Olympic competition there had been "the usual exchanges of friendship between members of the various teams. On some of the teams - I'm thinking of the Germans particularly - they spoke in a broken fashion better English than we did."
Walsh, who died of natural causes surrounded by his family at his Northern Virginia home, added: "You had these people competing. They were all trying to do the same thing. They were trying to speak to each other with various degrees of difficulty. It brings about a mixture between these people. You get by with stuttering and making hand movements. It was a great experience for me. And I enjoyed it."
Walsh returned to the Olympic fold at the 1972 Munich Games, where he served as team leader for USA Shooting, which won four medals.
The former G-man surpassed another American, Rudy Schrader, as the oldest Olympian ever on January 18, 2013. Schrader was a gymnast at the 1904 St Louis Olympics who died in 1981.
The oldest living Olympian is now Swiss Hans Erni, who participated in art competitions at the 1948 Olympics. The oldest living Olympian in a current Olympic sport is believed by Olympic historians to be 1936 Chinese discus thrower Guo Jie, who is 102.
Among the handful of living Olympic centenarians is Evelyn Furtsch Ojeda, who became the first US female Olympic champion to turn 100 on April 17 this year and is now, according to Olympic historians, the seventh oldest surviving Olympian.
Then 18, Furtsch Ojeda - who had been able to run at the Olympic trials in Chicago only thanks to the $190 raised door-to-door by the people of her hometown in Tustin, California - ran the second leg for the 4x100m relay team that won gold in the world record time of 46.9sec at the 1932 Los Angeles Olympics.
Speaking to garycohenrunning.com, Furtsch Ojeda recalled that the four women had never run together before and had practised baton exchanges during the Olympics at a local high school.
Anchored by six-foot blonde Wilhemina von Bremen, the US quartet won on a photo finish with Canada.
Furtsch Ojeda was an Olympic team-mate of Babe Didrikson Zaharias, who won the 80m hurdles and javelin and took silver in the high jump in Los Angeles.
"[Zaharias] was always bragging about herself," Furtsch Ojeda told garycohenrunning.com. "Saying things like, 'I am the greatest. She didn't interact with me personally...she was the star and got all of the publicity!"
Mike Rowbottom, one of Britain's most talented sportswriters, covered the London 2012 Olympics and Paralympics as chief feature writer for insidethegames, having covered the previous five summer Games, and four winter Games, for The Independent. He has worked for the Daily Mail, The Times, The Observer, The Sunday Correspondent and The Guardian. His latest book Foul Play – the Dark Arts of Cheating in Sport (Bloomsbury £12.99) is available at the insidethegames.biz shop. To follow him on Twitter click here.