Argentinian soccer star Emiliano Sala — and likely his pilot — were exposed to high levels of carbon monoxide before they were killed in a plane crash, a report revealed Wednesday.

The 28-year-old athlete, who had been signed to Cardiff City, had been flying to join his new team in January when the plane crashed in the English Channel, BBC reported.

Toxicology tests revealed that Sala had potentially fatal levels of carbon monoxide, which can cause seizure, unconsciousness or heart attack, according to the Air Accidents Investigations Branch.

Though his body was never found, pilot David Ibbotson also likely experienced carbon monoxide poisoning, the report said.

A spokesperson for the Sala family has called for further investigation of the doomed aircraft in response to the report.

“The family believes that a detailed technical examination of the plane is necessary,” spokesman Daniel Machover said in a statement. “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.”