Footballer Emilio Sala and pilot David Ibbotson, who were killed in an accident on 21 January while traveling on a private plane from Nantes to Cardiff, are exposed in the cockpit to harmful values of the toxic gas carbon monoxide.
The British Air Accidents Investigation Branch (AAIB) investigating aircraft accidents on Wednesday reported in an update (pdf) that the amount of carbon monoxide in Sala's blood is above the value that is considered potentially fatal.
Sala flew in January from his old club Nantes in France to his new club Cardiff City, but the plane disappeared over the Channel. His body was found two weeks later. Pilot Ibbotson's body is still missing.
The Argentinian striker Sala (28), with 17 million euros, was the most expensive purchase in the club history of Cardiff City.
See also: Sala died of head and chest injuries in a plane crash