Ayman Saad, the managing director of the UAE swimming federation, says on Tuesday the body of the 26-year-old Crippen was found with goggles still in place, suggesting he went down in "one second."
The president of the world swimming body said "overexertion" led toin waters above 86 degrees off Fujairah, about 60 miles east of Dubai.
CBS News correspondent Mark Phillips reported that the race organizers have been criticized for holding the event in temperatures higher than 80 degrees, and for not having enough boats out with the swimmers.
USA Swimming says it will open its own investigation.
The winner of the race, Germany's Thomas Lurz, criticized both FINA and race organizers on Sunday. He said the temperatures were too hot for racing, that FINA's open water schedule was too grueling and that organizers should have done more to ensure swimmers were safe.
"What we know initially is that he exerted himself more than he could, that's what we know," said FINA President Julio Maglione of Uruguay, attending an International Olympic Committee conference in Acapulco, Mexico.
"Apart from the investigation, we are awaiting a report from our technical director who says that everything was normal according to the regulations," Maglione said. "The medical report said it was huge overexertion, that's what they told me.
"It must have caused him to collapse."
"If the water's too warm and too salty, your dehydration level goes up so much faster," said Richard Shoulberg, Crippen's former coach. "I love him... we had a cup of coffee after every morning practice."