Investigators are now examining the two black boxes from the Russian passenger plane that crashed in Egypt’s Sinai Peninsula.
Russian officials say the jetliner broke up in midair, while Egyptian authorities say there was no proof for the Russian assertion.
Examination of the Russian plane’s black boxes — one recording on-board conversations and the other flight data — began on Tuesday.
Reports say the investigation could take weeks or even month, if the recordings were damaged.
The passenger jet, bound for St. Petersburg, crashed less than 30 minutes after taking off from the Red Sea resort of Sharm el-Sheikh.
All 224 people aboard died — most of them Russian tourists.
Reports say U.S. satellite systems detected heat around the jetliner before it crashed.
Analysts say it may indicate there was an explosion or disintegration of the plane, but it’s still unclear what caused it.
Russian officials earlier said the jet had broken up in midair.
But on Tuesday, Egypt’s civil aviation ministry said there were no facts to confirm the assertions, saying that no distress call had been received before the crash.