When the French government returned — and Algeria accepted — the skulls of 24 people taken as trophies during France’s brutal colonial rule, both nations celebrated the powerful gesture as a milestone in their efforts to rebuild ties.

The remains, part of one of Europe’s biggest skull collections at the Musée de l’Homme, or Museum of Mankind, in Paris, were presented by the Algerian government as “resistance fighters,” national heroes in Algeria for their sacrifice in chasing out French colonizers.

As recently as this month, when France’s prime minister, Élisabeth Borne, arrived in Algiers for a two-day visit, her Algerian counterpart, Aymen Benabderrahmane, expressed his satisfaction with the repatriation, which took place in 2020.

But documents from the museum and the French government, which were recently obtained by The New York Times, show that while six of the skulls returned were clearly identified as those of resistance fighters, the rest were not or were of uncertain origin. And all have remained France’s property even after they were handed over. Neither government has publicly acknowledged those facts as they seek to wring diplomatic benefit from the restitution.

The flawed return, whatever its intention, has instead emerged as an example of what several French academics and lawmakers say is a broader problem of often secretive, muddled and politically expedient repatriations by France that have fallen short of ambitions to right colonial-era wrongs.