KUALA LUMPUR, Malaysia -- The international search for the missing Malaysian jetliner expanded Friday further into the Indian Ocean amid signs the aircraft may have flown on for hours after its last contact with air-traffic control nearly a week ago, and more indicators suggested the Boeing 777's disappearance could involve criminal action
A U.S. official in Washington said that investigators are examining the possibility of "human intervention" in the plane's disappearance, adding it may have been "an act of piracy." The official, who wasn't authorized to talk to the media and spoke on condition of anonymity, said it also was possible the plane may have landed somewhere.
CBS News' Bob Orr reported that two communication systems on Malaysia Airlines Flight 370 were shut down separately in the moments before the flight disappeared from radar on Saturday; a data system and two transponders which relayed information about the jet's speed, altitude and location.
While a cascading electrical problem could feasibly cause that kind of staged electrical failure, Orr said it's also entirely possible somebody on the plane intentionally turned off the systems. And investigators say there's further evidence suggesting the jet did not crash immediately after being lost on radar; a transmitter on the plane tried for another four hours to ping satellites. That's an indication to analysts that the jet continued to fly for some time -- possibly as far as 2,500 miles from where it was last detected.
Investigators believe the plane, carrying 239 passengers and crew, turned and flew west from its intended flight path after it was last seen on radar on its intended flight path.
Malaysian military radar picked up unidentified blips moving away from the spot and then back across the Malaysian peninsula, toward the Strait of Malacca. Officials now think these blips represented the missing Boeing 777.
Officials have told CBS News the plane had enough fuel to carry it out to the west into the Indian Ocean, so the search is growing even larger. While they believe it likely crashed in water, it's also it possible landed somewhere.
Sources told the Reuters news agency on Friday, meanwhile, that the path Flight 370 appears to have taken after diverting from its intended route strongly suggests that a trained pilot was still in control of the aircraft.
The news agency said investigators believe the missing jet appeared to follow a known air navigational route, based on the radar blips seen by the Malaysian military.
That would have taken the plane into the Andaman Sea and toward the Indian Ocean, and according to Reuters, "could only have been set deliberately, either by flying the Boeing 777-200ER jet manually or by programming the auto-pilot."
Reuters cited another source as saying the official investigation was increasingly focused on the possibility that someone with training as a pilot deliberately diverted the flight.
"What we can say is we are looking at sabotage, with hijack still on the cards," a senior Malaysian police official told Reuters.
As that speculation intensified, police have said they are looking at the psychological background of the pilots, their family life and connections as one line of inquiry into flight MH370's disappearance, but there is no evidence linking them to any wrongdoing.
Some experts believe it is possible that one of the pilots, or someone with flying experience, hijacked the plane for some later purpose or committed suicide by plunging the aircraft into the sea.
Mike Glynn, a committee member of the Australian and International Pilots Association, said he considers pilot suicide to be the most likely explanation for the disappearance, as was suspected in a SilkAir crash during a flight from Singapore to Jakarta in 1997 and an EgyptAir flight in 1999.
"A pilot rather than a hijacker is more likely to be able to switch off the communications equipment," Glynn said. "The last thing that I, as a pilot, want is suspicion to fall on the crew, but it's happened twice before."
Glynn said a pilot may have sought to fly the plane into the Indian Ocean to reduce the chances of recovering data recorders, and to conceal the cause of the disaster..
Meanwhile, according to the South China Morning Post, Chinese scientists reported they had detected a small "seismic event" on the sea floor between Vietnam and Malaysia - where the plane was located at the approximate time that it disappeared.
However, Paul Caruso of the U.S. Geological Survey told USA Today that it was "unlikely" that a plane crash would be strong enough to produce the reported seismic event.
Orr said there has clearly been a ramping-up of American involvement in the investigation, as the Malaysians share more with U.S. aviation analysts who have a special expertise -- particularly in reading radar data.
"Also we have to say here there's a clear American interest on a couple of levels," Orr noted Friday on "CBS This Morning."
"The plane, of course, built by Boeing, and there were Americans on board," explained Orr. "But on top of that, this case could in the end involve crime or terrorism, and that could have future security implications."
Malaysia's Transport Minister Hishammuddin Hussein said Friday the search was expanding further afield -- not because of any new information about the plane's flight, but because the aircraft has not yet been found.
Malaysian officials declined to discuss when -- or even whether -- they had information about signals to satellites, and that they would release details only when verified. Hishammuddin said Malaysian investigators have worked with U.S. colleagues in Kuala Lumpur since Sunday.
"I hope within a couple of days to have something conclusive," he told a press conference.
If the plane had disintegrated during flight or had suffered some other catastrophic failure, all signals -- the pings to the satellite, the data messages and the transponder -- would be expected to stop at the same time. Experts say a pilot or passengers with technical expertise may have switched off the transponder in the hope of flying undetected.
No theory, however, has been ruled out in one of aviation history's most puzzling mysteries.
The Beijing-bound Boeing 777-200 last communicated with air traffic base stations east of Malaysia in the South China Sea, which for several days has the main focus of the search. Planes and ships also have been searching the Strait of Malacca west of Malaysia because of the blip on military radar suggesting the plane might have turned in that direction after the last confirmed contact.
If the plane flew another four hours, it could be much farther away.