New flight timeline: Suspicions arise that voice from cockpit may have tried to deceive ground controllers
*Final voice transmission may have occurred before communication systems were disabled
*Co-pilot spoke final words - "All right, good night"
*Search widened to include 26 countries
*Investigators haven't ruled out hijacking, sabotage, or pilot suicide
*No distress signal, no ransom notes, no parties claiming responsibility
Officials have released a new timeline suggesting the final voice transmission from the cockpit of the missing Malaysian plane may have occurred before any of its communications systems were disabled.
The latest development adds more uncertainty about who aboard might have been to blame.
The search for Flight 370, which vanished early March 8 while flying from Kuala Lumpur to Beijing with 239 people on board, has now been expanded deep into the northern and southern hemispheres.
Australian vessels scoured the southern Indian Ocean and China offered 21 of its satellites to help Malaysia in the unprecedented hunt.
Investigators say the plane was deliberately diverted during its overnight flight and flew off-course for hours.
They haven't ruled out hijacking, sabotage, or pilot suicide, and they are checking the backgrounds of the 227 passengers and 12 crew members, as well as the ground crew, to see if links to terrorists, personal problems or psychological issues could be factors.
Malaysian Defence Minister Hishammuddin Hussein said finding the plane was still the main focus, and he did not rule out that it might be discovered intact.
"The fact that there was no distress signal, no ransom notes, no parties claiming responsibility, there is always hope," he said at a news conference.
Malaysian Airlines CEO Ahmad Jauhari Yahya said an initial investigation indicated that the last words heard from the plane by ground controllers - "All right, good night" - were spoken by the co-pilot, Fariq Abdul Hamid.
Had it been a voice other than that of Fariq or the pilot, Zaharie Ahmad Shah, it would have been the clearest indication yet of something amiss in the cockpit before the flight went off-course.
Malaysian officials said earlier that those words came after one of the jetliner's data communications systems - the Aircraft Communications Addressing and Reporting System - had been switched off, suggesting the voice from the cockpit may have been trying to deceive ground controllers.
However, Mr Amhad said that while the last data transmission from ACARS - which gives plane performance and maintenance information - came before that, it was still unclear at what point the system was switched off, making any implications of the timing murkier.
The new information opened the possibility that both ACARS and the plane's transponders, which make the plane visible to civilian air traffic controllers, were turned off at about the same time.
It also suggests that the message delivered from the cockpit could have preceded any of the severed communications.
French investigators arriving in Kuala Lumpur to lend expertise from the two-year search for an Air France jet that crashed in the Atlantic Ocean in 2009 said they were able to rely on distress signals.
But that vital tool is missing in the Malaysia Airlines mystery because the flight's communications were deliberately silenced ahead of its disappearance, investigators say.
"It's very different from the Air France case. The Malaysian situation is much more difficult," said Jean Paul Troadec, a special adviser to France's aviation accident investigation bureau.
Malaysia's government sent diplomatic cables to all countries in the search area, seeking more planes and ships for the search, as well as to ask for any radar data that might help.
The search involves 26 countries and initially focused on seas on either side of Peninsular Malaysia, in the South China Sea and the Strait of Malacca.
Over the weekend, Prime Minister Najib Razak said investigators determined that a satellite picked up a faint signal from the aircraft about 71/2 hours after takeoff.
The signal indicated the plane would have been somewhere on a vast arc stretching from Kazakhstan in Central Asia to the southern reaches of the Indian Ocean.
Mr Hishammuddin said that searches in both the northern and southern stretches of the arc had begun, and that countries from Australia to China in the north and Kazakhstan in the west had joined the hunt.
Meanwhile, news emerged today that missing Malaysian Airlines plane reportedly flew as low as 5,000ft and used “terrain masking” to avoid radar detection for almost eight hours after it was apparently hijacked.
As dozens of nations continued to search for the plane, Malaysia’s New Straits Times newspaper reported that the Boeing 777 dropped to low altitude to avoid commercial radars.
Using a manoeuvre typically deployed by combat aircraft, the plane would have burnt far more fuel flying in the denser lower air.
Experts said a sharp drop in altitude – the plane was apparently flying as high as 45,000 feet - would have been noticeable for the passengers, but not deadly.
“The passengers would certainly know,” a former British military attaché told The Telegraph. “An emergency rapid descent would be very noticeable but not fatal. The fuel burn would be much higher at low level and you fly much slower across the ground. Plus you would be seen.
The revelation that the last communication from the cockpit occurred after the plane’s communications systems were turned off has effectively confirmed it was deliberately sabotaged and has focused police attention on the crew and passengers.
Malaysian police confirmed they are investigating Mohd Khairul Amri Selamat, a 29-year-old aviation engineer who was apparently flying from Kuala Lumpur to Beijing to carry out work on a plane in China.
"Yes, we are looking into Mohd Khairul as well as the other passengers and crew. The focus is on anyone else who might have had aviation skills on that plane," a police official told Reuters.
Khairul said on social media he worked for a Swiss-based jet charter firm, Execujet Aviation Group, though it has not yet confirmed that he worked for them. In his Facebook account in 2011, he identified himself as an employee of Execujet's Malaysian operations.
Khairul had recently bought a house in Malaysia and was last week described by his father, Selamat Omar as a caring son who would regularly visit his parents.
Malaysian authorities have confirmed that the backgrounds of all 239 passengers are being examined. Several foreign intelligence agencies have also been assisting with the checks.
Meanwhile, 26 countries are scouring a huge stretch of territory for any sign of the missing plane, including land, sea and aerial searches.
Dean Nelson, and Jonathan Pearlman, and Press Association