Emiliano Sala was exposed to harmful levels of carbon monoxide while on board the plane which crashed into the English Channel in January, investigators have found.
Argentine forward Sala was killed when flying from Nantes to Cardiff having completed a club-record £15 million move to the Bluebirds in January.
He and pilot David Ibbotson - whose body has not yet been found - were the only people on board the plane, and a report released by the Air Accidents Investigation Branch (AAIB) has revealed that the pair were exposed to the deadly gas following tests on Sala's blood.