"Errors of judgement" allowed the man who stabbed two women to death in Marseille to walk free after being arrested days earlier, an official report on the killings said Tuesday.
French Interior Minister Gerard Collomb announced a major reshuffle of staff in the centre-east Rhone region where the Tunisian attacker was held for theft and then released.
A government source said the regional representative of central government, Henri-Michel Comet, would be replaced.
On October 1, Ahmed Hanachi, a 29-year-old Tunisian, fatally stabbed two young women at Marseille's Saint-Charles train station, before being shot dead by police.
The Islamic State group's propaganda agency Amaq claimed the killer was one of its "soldiers", though a source close to the investigation told AFP no solid evidence linked him to the group.
Two days before the attack Hanachi was arrested for shoplifting in the eastern city of Lyon but was allowed to walk free the following day.
The official report by the government's inspectorate general (IGA) did not name any individuals at fault over the case, but spoke of "errors of judgement" and "serious faults" in the system around dealing with foreigners whose papers are not in order.
Sources close to the probe have said that the Lyon official who had authority to sign a detention and deportation order had been absent when Hanachi was arrested and that there was a lack of space in the local jail.
The attacker -- who had a history of petty crime but was not on a jihadist watch list -- used seven aliases.
France's lower house of parliament last week overwhelmingly approved a new counter-terrorism law, making permanent several controversial measures under the state of emergency that has been in place for nearly two years.