Footballer Emiliano Sala and his pilot were exposed to harmful levels of carbon monoxide inside the cockpit of their private plane before it crashed in to the Channel in January, air accident investigators said.
The plane went down on 21 January off the coast of Guernsey, killing him and his pilot, David Ibbotson.
Toxicology tests of Sala showed a carboxyhaemoglobin (a mixture of carbon monoxide and haemoglobin) saturation level of 58%.
According to investigators, anything over 50% is considered to be “potentially fatal.”
Investigators also assume that the pilot would also have been affected by exposure to the gas.
The team of investigators are now working with the aircraft manufacturers, and the US National Transportation Safety Board, to identify possible ways that carbon monoxide might have entered the aircarft’s cabin.
The Air Accidents Investigation Branch (AAIB) added: “Work is also continuing to investigate pertinent operational, technical, organisational and human factors which might have contributed to the accident.”
Daniel Machover, of Hickman and Rose solicitors, lawyers for the Sala family, said: “That dangerously high levels of carbon monoxide have been found in Emiliano’s body raises many questions for the family.
“How he died will be determined at the inquest in due course.
“The family believe that a detailed technical examination of the plane is necessary.
“The family and the public need to know how the carbon monoxide was able to enter the cabin. Future air safety rests on knowing as much as possible on this issue.
“Emiliano’s family call on the AAIB to salvage the wreckage of the plane without further delay.”
The wreckage of the plane was located on the 3 February this year and body was identified as that of the Argentinian footballer.
Sala had signed for Cardiff City from French club Nantes in January for £15 million on January 18.
59-year-old David Ibbotson from north Lincolnshire flew Sala from Cardiff to Nantes the following day, but the return flight crashed three days later.