The 1,650th victim of 9/11 was named after 22 years. More than 1,100 remain unidentified.

More than two decades after the 9/11 terrorist attacks, New York City officials have identified the remains of a Long Island man who was killed in the attacks on the World Trade Center.

John Ballantine Niven, 44, of Oyster Bay, New York, was a senior vice president at Aon Risk Services, an insurance firm on the 105th floor of tower two of the Trade Center complex, according to his obituary from The New York Times. Niven was survived by his mother, brother, two sisters, wife, and a son, who was 18 months old at the time of his death.

Niven is the 1,650th victim identified in the attacks on Sept. 11, 2001, that killed nearly 3,000 people after terrorists hijacked and crashed airplanes into the Twin Towers. In recent years, the New York City Medical Examiner’s office has identified victims' remains through advanced DNA analysis.

“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 Thursday. “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.”

About 40% — roughly 1,103 — of victims of the World Trade Center attack remain unidentified, according to according to a news release from the mayor’s office.

Just days before the 22nd memorial anniversary of the attacks last September, the medical examiner’s office said it had identified remains of a man and a woman, but their names were not made public at the request of their families. The two identifications were the first new identifications of World Trade Center victims since September 2021.

“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.”

'He touched many lives':Joseph Zadroga, advocate for 9/11 first responders, struck and killed in New Jersey parking lot

How many people died in 9/11?

On the morning of Sept. 11, United Airlines Flight 175 and American Airlines Flight 11 departed from Boston and was en route to California when hijackers crashed the airplanes into the north and south towers of the World Trade Center.

Two other flights, American Airlines Flight 77 and United Airlines Flight 93, were aimed to target in or near Washington, D.C. Flight 77 hit the Pentagon, while passengers attempted to overtake Flight 93 from hijackers before it crash-landed in Pennsylvania.

The attacks left 2,977 dead across New York, Washington, D.C. and Pennsylvania, according to the 9/11 Memorial and Museum. That total includes the 2,753 who died after the planes struck the twin towers, 184 people at the Pentagon, and 40 people who died in Pennsylvania. 

The 19 hijackers from the militant Islamic extremist group al-Qaeda also died in the attacks.

'Most complex forensic investigation'

DNA testing on the remains recovered in 2001 remains ongoing, according to the New York City Medical Examiner’s office. New technology has allowed the office to generate results after years of negative testing attempts.

Only a few full bodies were recovered when the twin towers collapsed, creating massive dust clouds that filled the air and left hundreds of highly populated city blocks covered in debris and other harmful particles, according to the World Trade Center Health Program.

With the emergence of new DNA technology, scientists have been working to connect more than 21,900 remains to individual victims in addition to testing samples collected from items found at the site, victims' relatives, or other remains.

"Recent identifications have been made possible through the adoption of next-generation sequencing technology, which is more sensitive and rapid than conventional DNA techniques," the New York City Medical Examiner’s office said. "Next-generation sequencing has been used by the U.S. military to identify the remains of missing American servicemembers."

The effort to identify World Trade Center victims is the “largest and most complex forensic investigation" in the history of the United States, according to the office.

DNA testing had become the primary means to identify the remains of the 9/11 attacks due to the fragmentation of bodies, which the National Institute of Standards and Technology said resulted from the high-velocity plane crashes and building collapses.

"Obtaining DNA results from recovered human remains was only part of the challenge of 9/11," according to the institute. "No one had ever attempted to correlate so many human remains with so many families before."

Contributing: Clare Mulroy, USA TODAY; The Associated Press