The four acoustic pings at the center of the search for Malaysia Airlines Flight 370 for the past seven weeks are no longer believed to have come from the plane's black boxes, a U.S. Navy official told CNN.
The acknowledgment came Wednesday as searchers wrapped up the first phase of their effort, having scanned 329 square miles of southern Indian Ocean floor without finding any wreckage from the Boeing 777-200.
Authorities now almost universally believe the pings did not come from the onboard data or cockpit voice recorders but instead came from some other man-made source unrelated to the jetliner that disappeared on March 8, according to Michael Dean, the Navy's deputy director of ocean engineering.
If the pings had come from the recorders, searchers would have found them, he said.
Dean said "yes" when asked if other countries involved in the search had reached the same conclusions.
"Our best theory at this point is that (the pings were) likely some sound produced by the ship ... or within the electronics of the Towed Pinger Locator," Dean said.
The pinger locator was used by searchers to listen for underwater signals.
"Always your fear any time you put electronic equipment in the water is that if any water gets in and grounds or shorts something out, that you could start producing sound," Dean explained.
He said it is not possible to absolutely exclude that the pings came from the black boxes, but there is no evidence now to suggest they did.
However, a U.S. Navy spokesman called Dean's statement to CNN "speculative and premature."
"I am not saying that what Michael Dean said was inaccurate," the spokesman said, "but what we are saying is that it is not his place to say it."
The Navy is continuing "to work with our partners to more thoroughly understand the data acquired by the Towed Pinger Locater," according to the spokesman.
"As such, we would defer to the Australians, as the lead in the search effort, to make additional information known at the appropriate time," the spokesman said.