(CNN) — A week after Malaysia Airlines Flight 370 vanished, the investigation shifted to passengers and crew after data showed the plane deviated due to deliberate action, Prime Minister Najib Razak said Saturday.
“Malaysian authorities have refocused their investigation on crew and passengers aboard,” Najib told reporters. “Evidence is consistent with someone acting deliberately from inside the plane.”
Najib stopped short of calling it a hijacking, saying investigators have not made a final determination.
“Despite media reports that the plane was hijacked, we are investigating all major possibilities on what caused MH370 to deviate,” he said.
Kazakhstan to Indian Ocean
In addition to the shift in focus, investigators have expanded search areas exponentially, and are no longer combing the South China Sea, the Prime Minister said.
Crew also searched the Straits of Malacca, the Andaman Sea and the Indian Ocean, but now data point in a different direction.
“The plane’s last communication with the satellite was in one of two possible corridors: a northern corridor stretching approximately from the border of Kazakhstan and Turkmenistan to northern Thailand, or a southern corridor stretching approximately from Indonesia to the southern Indian ocean,” he said.
The passenger jetliner disappeared on March 8, en route from Kuala Lumpur to Beijing, with 239 people aboard. It’s unclear who took the plane or what the motive was.
“Based on new satellite information, we can say with a high degree of certainty that the aircraft communications … system was disabled just before the aircraft reached the East Coast of peninsular Malaysia,” the Prime Minister said. “Shortly afterward, near the border between Malaysian and Vietnamese air traffic control, the aircraft’s transponder was switched off.”
Hopes of hijacking
Relatives held out hope that their loved ones will be found.
“It looks like there is increased possibility of a hijacking,” said Li, 31, whose husband is among the passengers. “Whatever the reason for the hijacking is, I hope they will not harm the passengers. They’re our loved ones.”
Though it’d lost communication, military radar showed the jetliner turned back, flew west over the the peninsular in Malaysia, and either turned northwest toward the Bay of Bengal or southwest into the Indian Ocean.
“Up until the point at which it left military primary radar coverage, these movements are consistent with deliberate action by someone on the plane,” he said.
Air traffic controllers outside Kuala Lumpur said they lost contact with the plane on March 8 at 1:30 a.m. local time, about 45 minutes after takeoff. The Prime Minister said its last communication with a satellite was at 8:11 a.m. the same day, but its precise location at the time was unclear.
Investigators are using such signals to determine how long and far it flew after it went incommunicado.
Police at pilot’s home
Shortly after the Prime Minister’s address, a van full of police arrived at the gated community home of pilot Zaharie Ahmad Shah, 53. The van later drove off.
Earlier Saturday, there was no police presence at the residence of his co-pilot, Fariq Ab Hamid, 27.
Theories and conspiracy theories have raged on what happened.
“There has been intense speculation,” Najib said. “We understand the desperate need for information on behalf of the families and those watching around the world. But we have a responsibility to the investigation and the families to only release information that has been corroborated.”
Hours before the Prime Minister’s announcement, U.S. officials told CNN the flight made drastic changes in altitude and direction after disappearing from civilian radar. The changes raised questions on who was at the controls of the jetliner when it vanished.
The more the United States learns about the flight’s pattern, “the more difficult to write off” the idea that some type of human intervention was involved, an official familiar with the investigation said.
CNN has learned that a classified analysis of electronic and satellite data suggests the flight likely crashed either in the Bay of Bengal or elsewhere in the Indian Ocean. The Prime Minister said some those areas have been searched.
Taken together, the data point toward speculation of a dark scenario in which someone took control of the plane for some unknown purpose, perhaps terrorism.
The jetliner was flying “a strange path,” a U.S. official said on condition of anonymity. The details of the radar readings were first reported by The New York Times on Friday.
Malaysian military radar showed the plane climbing to 45,000 feet soon after disappearing from civilian radar screens and then dropping to 23,000 feet before climbing again, the official said.
The question of what happened to the jetliner has turned into one of the biggest mysteries in aviation history, befuddling industry experts and government officials.
Fourteen countries, 43 ships and 58 aircraft are involved in the search, the Prime Minister said.
Shortly after he addressed reporters, China demanded that Malaysia provide more information on the investigation. China is sending technical experts to join the investigation.
Most of the passengers aboard are Chinese.
CNN’s Saima Mohsin, Chelsea J. Carter and Yuli Yang contributed to this report.