The Argentinian forward died on 21 January last year when the plane carrying him from Nantes to the Welsh capital crashed into the English Channel near Guernsey.
Sala was set to finalise a £15m move to the then-Premier League club, who were hoping the 28-year-old could score enough goals to help keep them in the division.
Twelve months on and Cardiff, who have so far refused to pay any of the transfer fee to Nantes, have called for an investigation into what they claim is “sufficient evidence of wrongdoing” by some of those involved in the deal.
The club issued a statement in response to an article in French sports newspaper L’Equipe, which claimed Nantes owner Waldemar Kita and Sala’s agent Willy McKay would be central to any potential probe.
Cardiff said there were still questions over why the Piper PA-46 Malibu plane crashed, and surrounding other issues such as “the use of illegal flights in the football industry and the role of intermediaries in player transfers”.
They added: “As a result of our investigation we believe there is sufficient evidence of wrongdoing that necessitates investigation by the French authorities of those responsible for the arrangement of the transfer on behalf of FC Nantes and for arranging the doomed flight.”
Cardiff said they had passed their information to the Parquet de Nantes to assist their efforts, adding: “We remain committed to establishing the full facts and adhering to any final decision on our financial liability in the transfer.”
The decision over the payment of the transfer fee will be made by the Court of Arbitration for Sport at some point this summer after Cardiff appealed a FIFA ruling that they should pay the first instalment of £5.2m.
Nantes, where Sala was a hero among the fans, have been critical of Cardiff’s conduct over the tragedy.
Cardiff, who are in the Sky Bet Championship following their relegation last season, have argued they were not liable for the full transfer fee because Sala was not officially their player when he died.
The deal that had been agreed was a club record transfer fee for Cardiff, who paid tribute to Sala last week to mark the first anniversary of his death.
Bluebirds manager Neil Harris and captain Sean Morrison were among those to attend a dedication service in the city and fans left flowers, banners and other tributes.
The service was also in honour of the pilot David Ibbotson, whose body was never found.
