Story highlights CNN analysts say figuring out motive of whoever steered plane off course is key

Background checks on some passengers complete with no red flags

Chinese families lose patience with Malaysian government and Malaysia Airlines

Authorities still looking at flight simulator taken from pilot's home

Where do you even begin to look, when the search area covers vast swaths of land and water, stretching thousands of miles, from Kazakhstan to the Indian Ocean?

That's the question for Malaysian officials and authorities from 24 other nations as people search for a ninth day, trying to find Malaysia Airlines Flight 370 and the 239 people on board.

As the search area grows bigger, authorities are also increasing their scrutiny of the pilots, searching their homes in the quest for clues. That includes a flight simulator from the captain's home.

It also includes interviewing the engineers who were in contact with MH370 before it took off, according to a statement from acting Transport Minister Datuk Seri Hishammuddin Tun Hussein to BERNAMA, Malaysia's official news agency. The transport minister characterized the interviews as "normal procedure."

"Police are still working on it. ... Nothing conclusive yet," a senior police official who has direct knowledge of the investigation told CNN on Sunday night, speaking on the condition of anonymity because the official was not authorized to speak to the press.

Photos: The search for MH370 Photos: The search for MH370 Two years after Malaysia Airlines Flight 370 went missing, a relative of one of the passengers burns incense in Beijing on March 8, 2016. Flight 370 vanished on March 8, 2014, as it flew from Kuala Lumpur, Malaysia, to Beijing. There were 239 people on board. Hide Caption 1 of 43 Photos: The search for MH370 On July 29, police carry a piece of debris on Reunion Island, a French territory in the Indian Ocean. A week later, authorities confirmed that the debris was from the missing flight. Hide Caption 2 of 43 Photos: The search for MH370 Staff members with the Australian Transport Safety Bureau examine a piece of aircraft debris at their laboratory in Canberra, Australia, on July 20. The flap was found in June by residents on Pemba Island off the coast of Tanzania, and officials had said it was highly likely to have come from Flight 370. Experts at the Australian Transport Safety Bureau, which is heading up the search for the plane, confirmed that the part was indeed from the missing aircraft. Hide Caption 3 of 43 Photos: The search for MH370 In late February, American tourist Blaine Gibson found a piece of plane debris off Mozambique, a discovery that renewed hope of solving the mystery of the missing flight. The piece measured 35 inches by 22 inches. A U.S. official said it was likely the wreckage came from a Boeing 777, which MH370 was. Hide Caption 4 of 43 Photos: The search for MH370 Relatives of the flight's passengers console each other outside the Malaysia Airlines office in Subang, Malaysia, on February 12, 2015. Protesters had demanded that the airline withdraw the statement that all 239 people aboard the plane were dead. Hide Caption 5 of 43 Photos: The search for MH370 A police officer watches a couple cry outside the airline's office building in Beijing after officials refused to meet with them on June 11, 2014. The couple's son was on the plane. Hide Caption 6 of 43 Photos: The search for MH370 Members of the media scramble to speak with Azharuddin Abdul Rahman, director general of Malaysia's Civil Aviation Department, at a hotel in Kuala Lumpur, Malaysia, on May 27, 2014. Data from communications between satellites and the missing flight was released the day before, more than two months after relatives of passengers said they requested it be made public. Hide Caption 7 of 43 Photos: The search for MH370 Operators aboard the Australian ship Ocean Shield move Bluefin-21, the U.S. Navy's autonomous underwater vehicle, into position to search for the jet on April 14, 2014. Hide Caption 8 of 43 Photos: The search for MH370 A member of the Royal New Zealand Air Force looks out of a window while searching for debris off the coast of western Australia on April 13, 2014. Hide Caption 9 of 43 Photos: The search for MH370 The HMS Echo, a vessel with the British Roya; Navy, moves through the waters of the southern Indian Ocean on April 12, 2014. Hide Caption 10 of 43 Photos: The search for MH370 A Royal Australian Air Force AP-3C Orion, on a mission to drop sonar buoys to assist in the search, flies past the Australian vessel Ocean Shield on April 9, 2014. Hide Caption 11 of 43 Photos: The search for MH370 A relative of a missing passenger cries at a vigil in Beijing on April 8, 2014. Hide Caption 12 of 43 Photos: The search for MH370 Australian Defense Force divers scan the water for debris in the southern Indian Ocean on April 7, 2014. Hide Caption 13 of 43 Photos: The search for MH370 A towed pinger locator is readied to be deployed off the deck of the Australian vessel Ocean Shield on April 7, 2014. Hide Caption 14 of 43 Photos: The search for MH370 A member of the Royal New Zealand Air Force looks at a flare in the Indian Ocean during search operations on April 4, 2014. Hide Caption 15 of 43 Photos: The search for MH370 On March 30, 2014, a woman in Kuala Lumpur prepares for an event in honor of those aboard Flight 370. Hide Caption 16 of 43 Photos: The search for MH370 The sole representative for the families of Flight 370 passengers leaves a conference at a Beijing hotel on March 28, 2014, after other relatives left en masse to protest the Malaysian government's response to their questions. Hide Caption 17 of 43 Photos: The search for MH370 A member of the Royal Australian Air Force is silhouetted against the southern Indian Ocean during the search for the missing jet on March 27, 2014. Hide Caption 18 of 43 Photos: The search for MH370 Flight Lt. Jayson Nichols looks at a map aboard a Royal Australian Air Force aircraft during a search on March 27, 2014. Hide Caption 19 of 43 Photos: The search for MH370 People in Kuala Lumpur light candles during a ceremony held for the missing flight's passengers on March 27, 2014. Hide Caption 20 of 43 Photos: The search for MH370 Malaysian Prime Minister Najib Razak, center, delivers a statement about the flight on March 24, 2014. Razak's announcement came after the airline sent a text message to relatives saying it "deeply regrets that we have to assume beyond any reasonable doubt that MH 370 has been lost and that none of those onboard survived." Hide Caption 21 of 43 Photos: The search for MH370 Grieving relatives of missing passengers leave a hotel in Beijing on March 24, 2014. Hide Caption 22 of 43 Photos: The search for MH370 A passenger views a weather map in the departures terminal of Kuala Lumpur International Airport on March 22, 2014. Hide Caption 23 of 43 Photos: The search for MH370 A Chinese satellite captured this image, released on March 22, 2014, of a floating object in the Indian Ocean, according to China's State Administration of Science. It was a possible lead in the search for the missing plane. Surveillance planes were looking for two objects spotted by satellite imagery in remote, treacherous waters more than 1,400 miles from the west coast of Australia. Hide Caption 24 of 43 Photos: The search for MH370 Satellite imagery provided by the Australian Maritime Safety Authority on March 20, 2014, showed debris in the southern Indian Ocean that could have been from Flight 370. The announcement by Australian officials raised hopes of a breakthrough in the frustrating search. Hide Caption 25 of 43 Photos: The search for MH370 Another satellite shot provided by the Australian Maritime Safety Authority shows possible debris from the flight. Hide Caption 26 of 43 Photos: The search for MH370 A distraught relative of a missing passenger breaks down while talking to reporters at Kuala Lumpur International Airport on March 19, 2014. Hide Caption 27 of 43 Photos: The search for MH370 On March 18, 2014, a relative of a missing passenger tells reporters in Beijing about a hunger strike to protest authorities' handling of information about the missing jet. Hide Caption 28 of 43 Photos: The search for MH370 U.S. Navy crew members assist in search-and-rescue operations in the Indian Ocean on March 16, 2014. Hide Caption 29 of 43 Photos: The search for MH370 Members of the Chinese navy continue search operations on March 13, 2014. After starting in the sea between Malaysia and Vietnam, the plane's last confirmed location, search efforts expanded west into the Indian Ocean. Hide Caption 30 of 43 Photos: The search for MH370 A Vietnamese military official looks out an aircraft window during search operations March 13, 2014. Hide Caption 31 of 43 Photos: The search for MH370 Malaysian air force members look for debris near Kuala Lumpur on March 13, 2014. Hide Caption 32 of 43 Photos: The search for MH370 Relatives of missing passengers wait for the latest news at a hotel in Beijing on March 12, 2014. Hide Caption 33 of 43 Photos: The search for MH370 A member of the Vietnamese air force checks a map while searching for the missing plane on March 11, 2014. Hide Caption 34 of 43 Photos: The search for MH370 A Vietnamese air force plane found traces of oil that authorities had suspected to be from the missing Malaysia Airlines plane, the Vietnamese government online newspaper reported on March 8, 2014. However, a sample from the slick showed it was bunker oil, typically used to power large cargo ships, Malaysia's state news agency, Bernama, reported on March 10, 2014. Hide Caption 35 of 43 Photos: The search for MH370 A U.S. Navy Seahawk helicopter lands aboard the USS Pinckney to change crews on March 9, 2014, before returning to search for the missing plane in the Gulf of Thailand. Hide Caption 36 of 43 Photos: The search for MH370 Buddhist monks at Kuala Lumpur International Airport offer a special prayer for the missing passengers on March 9, 2014. Hide Caption 37 of 43 Photos: The search for MH370 Members of a Chinese emergency response team board a rescue vessel at the port of Sanya in China's Hainan province on March 9, 2014. Hide Caption 38 of 43 Photos: The search for MH370 The rescue vessel sets out from Sanya in the South China Sea on March 9, 2014. Hide Caption 39 of 43 Photos: The search for MH370 Malaysian Prime Minister Najib Razak, center, arrives to meet family members of missing passengers at the reception center at Kuala Lumpur International Airport on March 8, 2014. Hide Caption 40 of 43 Photos: The search for MH370 A relative of two missing passengers reacts at their home in Kuala Lumpur on March 8, 2014. Hide Caption 41 of 43 Photos: The search for MH370 Chinese police at the Beijing airport stand beside the arrival board showing delayed Flight 370 in red on March 8, 2014. Hide Caption 42 of 43 Photos: The search for MH370 Malaysia Airlines Group CEO Ahmad Juahari Yahya, front, speaks during a news conference at a hotel in Sepang on March 8, 2014. "We deeply regret that we have lost all contacts" with the jet, he said. Hide Caption 43 of 43

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With news that the Boeing 777-200ER might have flown for six and a half hours after its transponder stopped sending signals March 8, officials said the expanding search area extends over 11 countries, stretching as far north as Kazakhstan, a large nation in Central Asia far from any ocean.

"This is a significant recalibration of the search," Malaysia's acting Transportation Minister Hishammuddin Hussein said Sunday.

There are still more questions than answers about the missing flight. Figuring out the motive of whoever apparently steered the plane off course is key, analysts told CNN Sunday.

"I think they had an end game in mind from the very beginning," CNN aviation analyst Jim Tilmon said, "and they have executed a lot of things that have led us down a road. Are we going to the right place? I'm not sure."

The plane disappeared on March 8, en route from Kuala Lumpur to Beijing. Airline CEO Ahmad Jauhari Yahya said Sunday the missing passenger jet took off with its normal amount of fuel needed for the roughly six-hour flight and did not have extra fuel on board that could have extended its range.

One of the nations involved in the search, Pakistan, said Sunday that the plane never showed up on its civilian radars and would have been treated as a threat if it had.

The Times of India reported that India's military also said there was no way the plane could have flown over India without being picked up on radar.

A study of the flight's cargo manifest showed there were no dangerous materials on board that concerned investigators, he told reporters.

Investigators are still looking into the backgrounds of the passengers to see whether any of them were trained pilots.

"There are still a few countries who have yet to respond to our request for a background check," said Khalid Abu Bakar, inspector general of the Royal Malaysian Police Force. "But there are a few ... foreign intelligence agencies who have cleared all the(ir) passengers."

U.S. intelligence officials are leaning toward the theory that "those in the cockpit" -- the captain and co-pilot -- were responsible for the mysterious disappearance, a U.S. official with direct knowledge of the latest thinking told CNN.

The official emphasized no final conclusions have been drawn and all the internal intelligence discussions are based on preliminary assessments of what is known to date.

Malaysian Prime Minister Najib Razak told reporters on Saturday that the plane veered off course due to apparent deliberate action taken by somebody on board.

'Someone acting deliberately'

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The first clue that the captain or co-pilot may have been involved stems from when the plane made a sharp, deliberate turn just after it last communicated with Kuala Lumpur air traffic controllers, and before it would have to communicate with Vietnamese controllers, according to the U.S. official with knowledge of the latest intelligence thinking.

"This is the perfect place to start to disappear," the official said.

Adding to the intrigue, ABC News reported that the dramatic left turn was preprogrammed into the plane's navigation computer. It's a task that would have required extensive piloting experience.

Two senior law enforcement officials also told ABC that new information revealed the plane performed "tactical evasion maneuvers" after it disappeared from radar. CNN was unable to confirm these reports.

Military radar showed the jetliner flew in a westerly direction back over the Malaysian Peninsula, Najib said. It is then believed to have either turned northwest toward the Bay of Bengal or southwest elsewhere in the Indian Ocean, he said.

"Evidence is consistent with someone acting deliberately from inside the plane," the Prime Minister said, officially confirming the plane's disappearance was not caused by an accident. "Despite media reports that the plane was hijacked, we are investigating all major possibilities on what caused MH370 to deviate."

The unconfirmed possibility that the plane could be on land means authorities need to answer that question -- and fast, analysts said.

"Time is even more of the essence. If this airplane has been taken to be used as a weapon, then the time that has been taken to prepare the aircraft for whatever deed is the plan, obviously to thwart that, it's all about time," said Shawn Pruchnicki, who teaches aviation safety and accident investigation at The Ohio State University.

Tilmon said whoever deliberately steered the plane off course likely did it with help. But what's next is anyone's guess, he said.

"We have been behind them all along, so now, if they had a plan, and if that plan included being able to set down someplace and refuel a little bit, we are looking at something that we may never see the end of," he said.

The pilots

On Saturday, Malaysian police searched the home of pilot Zaharie Ahmad Shah, 53. Zaharie lives in an upscale, gated community in Shah Alam, outside Malaysia's capital, Kuala Lumpur.

The Ministry of Transport said Sunday that police were examining a flight simulator found at the pilot's house.

It's somewhat common among aviation enthusiasts to use online flight simulator programs to replicate various situations. Simulators allow users to virtually experience scenarios in various aircraft. Programs can simulate flight routes, landings and takeoffs from actual airports.

Two vans were loaded with small bags, similar to shopping bags, at the home of the co-pilot, 27-year-old Fariq Ab Hamid, according to a CNN crew who observed activities at the residence. It was unclear whether the bags were taken from the home, and police made no comment about their activities there.

Andaman and Nicobar Islands

Najib made clear in a news conference that in light of the latest developments, authorities have refocused their investigation to the crew, ground staff and passengers on board.

Hishammuddin, the transportation minister, told reporters the pilots didn't request to work together.

Peter Chong, a friend of Zaharie's, said he had been in the pilot's house and tried the simulator.

"It's a reflection of his love for people -- because he wants to share the joy of flying with his friends," Chong said.

He was bothered by speculation about the captain's credibility and questions about possible ties to terrorism.

"I think it is a little bit insensitive and unfair to the family," he said, adding he thought there was no evidence to suggest any ulterior motives on Shah's part.

A senior U.S. law enforcement official told CNN that investigators are carefully reviewing the information so far collected on the pilots to determine whether there is something to indicate a plan or a motive.

"In any criminal investigation, the most important analysis is what's the motive," said Mary Schiavo, a CNN aviation analyst and former inspector general for the U.S. Department of Transportation. "I think right now, they have to look for it, and they have to rule it out, if they can, with their own pilots, so they can start looking for motives elsewhere."

Undoubtedly, authorities will scour through the flight manifest and look further to see whether any of the passengers on board had flight training or connections to terror groups.

According to The New York Times, one of the passengers was an aviation engineer on his way to Beijing to work for a private-jet company.

Kazakhstan to Indian Ocean

As the focus of the investigation has shifted, so, too, has the focus of the search.

Information from international and Malaysian officials indicates the jet may have flown for more than seven hours after the last contact with the pilots.

Flight 370 took off from Kuala Lumpur at 12:41 a.m. March 8. The last satellite communication from the plane occurred at 8:11 a.m., Najib said, well past the scheduled arrival time in Beijing. It is possible this contact could have been made from the ground, as long as the airplane still had electrical power, Malaysia's civil aviation chief Azharuddin Abdul Rahman said Sunday.

That last communication, Najib said, was in one of two possible traffic corridors shown on a map released to reporters. A northern arc stretches from the border of Kazakhstan and Turkmenistan to northern Thailand, and a southern arc spans from Indonesia to the southern Indian Ocean.

"Due to the type of satellite data, we are unable to confirm the precise location of the plane when it last made contact with the satellite," Najib said.

Because the northern parts of the traffic corridor include some tightly guarded airspace over India, Pakistan and even some U.S. installations in Afghanistan, U.S. authorities believe it more likely the aircraft crashed into waters outside of the reach of radar south of India, a U.S. official told CNN. If it had flown farther north, it's likely it would have been detected by radar.

Malaysia's Ministry of Transport said Sunday that both the northern and southern corridors are being treated with equal importance. Malaysian officials are working with 25 countries, many of them along the corridors. They include Kazakhstan, Uzbekistan, Kyrgyzstan, Turkmenistan, Pakistan, Bangladesh, India, China, Myanmar, Laos, Vietnam, Thailand, Indonesia, Australia, France, the United Kingdom and the United States.

Afghanistan's Ministry of Transport said it has joined the search, but said there is no evidence the plane flew over Afghan soil.

Separately, India has "temporarily halted" its search for the missing plane while Malaysian authorities reassess the situation, according to a top military official.

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"We are conserving our assets for now," Rear Adm. Sudhir Pillai, the chief of staff of India's joint Andaman and Nicobar command, said Sunday. "We are on a standby."

He said the Malaysians are reviewing India's deployment.

Families at boiling point

For the families and loved ones of those aboard Flight 370, tensions boiled over Sunday in Beijing at the daily briefing by Malaysia Airlines.

Nine days after the plane went missing, patience is running thin with officials.

Before a packed room, one man told them that the families have already lost faith.

"A liar can lie once, twice or three times, but what's the point (to) keep lying?" he said. "What we ask for is the truth. Don't hide things from us."

In the face of mounting criticism over its handling of the situation, Malaysia Airlines has defended its actions, saying it took time to verify satellite signals and give authorities a chance to analyze their significance before releasing information.

But at Sunday's Beijing briefing, a majority of the people in the room stood up when the man asked how many had lost trust in the airline and the Malaysian government.

Another man rushed the front of the room and tried to throw a punch but was stopped.

The airline has been picking up the tab for families of the Chinese passengers to stay in Beijing during the ordeal.

China is sending technical experts to join the investigation, and two Chinese search vessels headed for the Strait of Malacca, according to Xinhua.

People are across the world have shown their support for those involved.

During his weekly Sunday message following prayers at the Vatican, Pope Francis asked the crowd to pray for the crew members and passengers of the missing Malaysia Airlines plane and their families. "We are close to them in this difficult moment," Pope Francis said.