NEW YORK (AFP) - Nearly 15 years after the Sept 11, 2001 attacks, a firefighter who disappeared at the World Trade Center that day has finally been laid to rest.
The family buried two blood samples Battalion Chief Lawrence Stack had donated a few months prior to the attacks, after waiting in vain for the authorities to recover his remains, nearly giving up hope.
Hundreds of firefighters, New York Mayor Bill de Blasio and Commissioner of the New York City Fire Department (FDNY) Daniel Nigro attended the full-honours funeral held for the 58-year-old at Long Island's Saints Philip and James Catholic Church, near New York, according to the FDNY.
"He survived the collapse of the South Tower, quickly freed himself from fallen debris and continued to courageously help others," Mr Nigro said.
"He bravely and selflessly stayed to help an injured New Yorker with a severed Achilles tendon. He worked feverishly to find a way to save that person and remove them from harm, as the North Tower collapsed, taking both their lives," he added.
Mr Stack's two sons, also firefighters, were among those who carried the coffin, draped in an American flag.
The family obtained Mr Stack's blood because the career firefighter had registered on a list of potential bone marrow donors. In doing so he gave a blood sample for type matching, which was discovered on ice at a storage facility in Minnesota, according to local press.
The blood was to be buried with full departmental honours at the Calverton National Cemetery on eastern Long Island following the religious ceremony.
The firefighter's FDNY jacket was discovered beneath the rubble at ground zero, but search teams never found traces of his body.
As the months turned into years, his widow Theresa had decided that after 15 years, it was time to end the wait. Mr Stack's funeral took place on what would have been the couple's 49th wedding anniversary.
Of the 2,763 people killed in the Sept 11, 2001 attacks, only 1,637 have been identified, accounting for 65 per cent of the recovered remains. The rest - some of it microscopic - is so damaged that it cannot be identified.
Of the firefighters who rushed to the World Trade Center as tragedy unfolded that day, 343 were killed.
The authorities were unable to recover remains for 127 of them, said Mr Nigro.
