New York City officials announced they had identified remains of Ryan D Fitzgerald, a 26-year-old currency trader; Barbara A Keating, a 72-year-old retired nonprofit executive; and another woman whose name authorities kept private at her family's request.
The matches were made through now-improved DNA testing of minute remains found more than 20 years ago amid the wreckage of the World Trade Centre after the al-Qaida hijacked-plane attacks.
"Each new identification testifies to the promise of science and sustained outreach to families despite the passage of time," chief medical examiner Dr Jason Graham said in a statement.
"We continue this work as our way of honouring the lost."
Keating's son, Paul Keating said he was amazed and impressed by the enduring endeavour.
"It's just an amazing feat, gesture," he told the New York Post.
He said genetic material from part of his mother's hairbrush was matched to DNA samples from relatives.
A bit of his mother's ATM card was the only other trace of her ever recovered from the debris, he said.
Barbara Keating was a passenger on the Boston-to-Los Angeles-bound American Airlines Flight 11 when hijackers slammed it into the World Trade Centre.
She was headed home to Palm Springs, California, after spending the summer on Massachusetts' Cape Cod.
Keating had spent her career in social services, including a time as executive director of the Big Brothers Big Sisters of South Middlesex, near Boston.
In retirement, she was involved in her Catholic church in Palm Springs.
Fitzgerald, who lived in Manhattan, was working at a financial firm at the trade centre, studying for a master's degree in business and talking about a long-term future with his girlfriend, according to obituaries published at the time.
In all, nearly 3000 people were killed when the hijackers crashed jetliners into the trade centre's twin towers, the Pentagon and a field in southwest Pennsylvania.
The vast majority of the victims, more than 2700, perished at the trade centre.
Keating's and Fitzgerald's names are already inscribed on the monument to the victims at the National September 11 Memorial in New York City.
The New York medical examiner's office has tested and retested fragments as techniques advanced over the years and created new prospects for reading genetic code diminished by fire, sunlight, bacteria and more.
"We hope the families receiving answers from the Office of Chief Medical Examiner can take solace in the city's tireless dedication to this mission," New York Mayor Eric Adams said.
