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Can Flight 804 victims' remains offer clues?

Last Updated May 24, 2016 7:45 AM EDT

CAIRO -- An Egyptian forensic official told The Associated Press on Tuesday that human remains from the EgyptAir flight 804 crash in the Mediterranean suggest there was an explosion on the aircraft before it went down, but the claim was later rejected by outside experts and Egypt's government.

The AP said the official was a member of the Egyptian investigation team who had personally examined the dozens of pieces of recovered remains at a morgue.

"There isn't even a whole body part, like an arm or a head," said the official who spoke to The AP on condition of anonymity. "The logical explanation is that it was an explosion."

The official did not suggest any trace of explosives had been found on the human remains or other items recovered from the wreckage.

If the forensic investigator's theory had been confirmed, it would have been the first tangible indication that a blast led to the crash of the Airbus A320 as it flew toward Alexandria, Egypt from Paris.

But CBS News transportation safety analyst and former chairman of the National Transportation Safety Board (NTSB) Mark Rosenker urged caution over drawing any conclusions based solely on the size of the remains recovered thus far.

"We just don't know," Rosenker said. "Until we get people to go on the record with their names we don't know what is happening."

"This is an interesting statement, but I would have to look at it with sceptisism," Rosenker said, adding that the discovery of small peices of human remains after a plane crash would not be atypical -- regardless of the cause of the crash.

Later Tuesday, the head of Egypt's forensics agency rejected the claim by the anonymous official as "completely false."

Egyptian state news agency MENA said Hesham Abdelhamid had released a statement calling the claims "mere assumptions that did not come from the Forensics Authority."

All 66 people on board EgyptAir flight 804 are presumed to have died in the crash. Egyptian officials have told CBS News they believe it was more likely a terror attack that brought the plane down than a technical failure.

The comments about the remains came as a French Naval ship arrived to the search area -- about 180 miles north of Egypt's coast -- to help in the effort to recover the plane's flight data and cockpit voice recorders, or black boxes as they are commonly known.

But as CBS News correspondent Holly Williams reports, there isn't just mystery surrounding this crash, but confusion. A senior Egyptian official has now said that radar data from the Greek government about the plane's last moments in the air was wrong.

The Greek government said that just after the plane left Greek airspace it swerved wildly and plummeted, before finally falling off the radar screen.

Egypt's head of air navigation services, however, denied that claim on Monday, saying the plane was flying normally at cruising altitude when last seen on Egyptian radar.

There's confusion, too, about the plane's black boxes. An Egyptian government official told CBS News they had been approximately located by the pings they emit, though not retrieved.

That was also reported by media in Egypt, but so far, there's been no official confirmation, and others have denied it.

Meanwhile, data published by an aviation industry website appears to show that there was smoke on board the jet in the minutes before it crashed, but experts say the smoke alarms could also have been triggered by a sudden loss of pressure in the cabin.

Even the black boxes may not tell us what went wrong; it depends on the information they contain -- if they're recovered.

Williams notes that the crash of EgyptAir flight 804 was just the latest incident in a truly disastrous year for Egyptian aviation.

A Russian Metrojet passenger plane was downed by a suspected ISIS bomb in the country's volatile Sinai Peninsula in October, and another EgyptAir passenger plane was hijacked by a man wearing a fake suicide belt in March.