The remains of a Long Island man killed at the World Trade Center on 9/11 have been identified more than two decades after the 2001 attacks, the New York City medical examiner’s office announced Thursday.

John Ballantine Niven, 44, was an executive at Aon Risk Services, an insurance firm on the 105th floor of tower two of the trade center complex, according to obituaries at the time. He and his young family split time between Manhattan and Oyster Bay, where he grew up.

Ellen Niven, his wife, said Thursday that she and their son Jack, who was just 18 months old when his father died, are grateful for the “extraordinary efforts” of city officials continuing the difficult task of identifying victims’ remains.

“It is certainly emotional for me, and I’m sure many others, to hear many years later that DNA has been found,” she wrote in an email. “It’s a real tribute to the City of New York and the teams working behind the scenes all these years to honor that mantra ‘Never Forget.’ My son and I are so appreciative of this tremendous endeavor.”

Niven is the 1,650th victim identified from the deadliest act of terrorism on American soil, when hijackers crashed airplanes into the Twin Towers, killing 2,753 people.

“While the pain from the enormous losses on September 11th never leaves us, the possibility of new identifications can offer solace to the families of victims,” New York City Mayor Eric Adams said in a statement. “I’m grateful for the ongoing work from the Office of Chief Medical Examiner that honors the memory of John Ballantine Niven and all those we lost.”

The medical examiner’s office has been using advanced DNA analysis to identify victim remains in recent years.

Ahead of the anniversary of the attacks last September, the office identified the remains of a man and a woman, though their names were not made public at the request of their families.

“We will forever remember our heroes who perished on 9/11 and we appreciate the continuous efforts of forensic experts to help identify victims,” Oyster Bay Supervisor Joseph Saladino said in a separate statement. “We’re hopeful that this amazing advance in technology helps bring peace to Mr. Niven’s family and allows him to eternally rest in peace.”

Roughly 40 percent of victims of the World Trade Center attack have yet to have their remains identified, as few full bodies were recovered when the giant towers collapsed.

But as DNA testing has evolved, so have efforts to connect more than 21,900 remains to individual victims. In some cases, scientists have gone back to the same pieces 10 or more times, hoping new technology will provide answers.

The 9/11 attacks killed nearly 3,000 people in New York, at the Pentagon and near Shanksville, Pennsylvania.