President Emmanuel Macron said on Thursday that Maurice Audin, a communist pro-independence activist who disappeared in 1957, "died under torture stemming from the system instigated while Algeria was part of France."
Macron, who paid a visit to Audin's widow on Thursday, was also set to announce "the opening of archives on the subject of disappeared civilians and soldiers, both French and Algerian."
During the 1954-62 war, which claimed some 1.5 million Algerian lives, French forces cracked down on independence fighters in the colony ruled by Paris for 130 years.
Macron told Audin's widow: "The only thing I am doing is to acknowledge the truth."
Josette Audin told reporters at her apartment in the east Paris suburb of Bagnolet: "I never thought this day would come."
Starting with former President Jacques Chirac in 2003, French leaders have at various points denounced the suffering that the occupation of Algeria caused the indigenous population, before walking back or tempering their statements.
But none until Macron, however, acknowledged France's responsibility in the torture of Algerian detainees.
During the war, the French government censored newspapers, books, and films that claimed it had used torture. After the war, atrocities committed by its troops remained a taboo subject in French society.
Rim-Sarah Alouane, an international human rights jurist and a PhD candidate in public law at Toulouse University, told Al Jazeera that justice was finally being served.
"I think this very welcoming decision by President Macron was the natural next step to take in this very heavy history. It had to be done for the sake of both countries," Alouane said.
"A lot of mysteries around the disappearances of people who fought during the Algerian war of independence remain, mysteries that have affected thousands and thousands of families."
Alouane said while the declaration does not amount to an apology, it's an important step given that colonisation is still a taboo subject in France.
Historian Sylvie Thenault said the French state's acknowledgement that Audin's death resulted from a "system" pointed to a broader recognition of wrongdoing.
"Through recognition of the state's responsibilities in the disappearance of Maurice Audin, have the state's responsibilities in all disappearances in Algiers in 1957 not been recognised?" she wrote in The Conversation, a news website.
Facing the past
Macron, the first president born after the conflict, sparked controversy on the campaign trail last year by declaring that France's colonisation of Algeria was a "crime against humanity".
He later walked back the comments calling for "neither denial nor repentance" over France's colonial history.
Reporting from Paris, Al Jazeera's Natacha Butler said Thursday's announcement had deep symbolic meaning and would bring closure for Audin's widow 60 years later - and may help others with the opening of the archives.
"It's a very significant statement indeed. It closes a chapter for her, and it perhaps opens one for others because relatives of people who died at the time will be able to find out what happened to their loved ones," she said.
An assistant professor at the University of Algiers, Audin was 25 when he was arrested at his home - likely by French soldiers - accused of harbouring communist independence fighters.
The father-of-three was tortured repeatedly in a villa in the Algiers neighbourhood of El Biar. Josette Audin was told 10 days later her husband had escaped while being transferred between jails.
This remained the official version of events until 2014, when Macron's predecessor, Francois Hollande, acknowledged Audin died in detention.
A 2014 book by journalist Jean-Charles Deniau claimed the mathematician was killed by a French army officer on the orders of General Jacques Massu.
That order was confirmed by another general, Paul Aussaresses, who died in 2013 after admitting he tortured and killed dozens of prisoners.