Missing Malaysia Jet Turned Back Before Disappearing

The mystery behind the disappearance of a Malaysia Airlines flight is deepening as authorities revealed Tuesday that the plane turned around and flew hundreds of miles back toward land before it seemingly vanished.

The Malaysian military said it has radar evidence showing the missing Boeing 777 jetliner was heading northeast toward China when it changed course back to the Malacca Strait, hundreds miles away from the last location reported by civilian authorities.

The Malaysian newspaper Berita Harian reports air force radar detected the airliner near Pulau Perak, at the northern approach to the strait. A high-ranking military official said the aircraft was believed to be flying low.

Today, authorities appeared to rule out one theory, saying two men traveling on stolen passports were likely not terrorists. They identified both men as Iranians, one posing as an Italian, the other as an Austrian.

The mother of one of the men told police he was seeking asylum in Germany.

"The interest [in an Iranian terrorist plot] seems to be dying down because these might just be people who were being smuggled," Interpol Secretary Ron Noble said.

The scramble for new leads has intensified. Police say they're looking at the possibility of hijacking, sabotage, or psychological problems with the passengers or crew.

Investigators also haven't ruled out catastrophic mechanical failure or an accident. But after four days, there are still no sign of the plane or any wreckage.

Hishammuddin Hussein, Malaysian Minister of Defense and Acting Transport Minister, called rescue efforts,"probably one of the largest search and rescue operations [ever]."

If the wreckage is in the ocean, special ships or submarines need to be within 5 to 10 miles to hear the pinging noise from the black boxes. Finding them and the wreckage will be crucial to figuring out what happened.

"We need to keep an open mind, continue the search, find the wreckage, find those black boxes and begin to solve this mystery," said Deputy Assistant Secretary of State Ret. Col. Stephen Ganyard, a former fighter pilot with the Marines.

"Nothing causes an airplane to come down from 35,000 feet other than things that can be catastrophic," Ganyard said.

If the plan did crash, the clock is ticking. The batteries on the plane's black box only last for 30 days.