The mystery around what happened to Malaysian Airlines Flight 370 is over according to a Canadian aviation expert who believes the plane was intentionally flown into the southern Indian Ocean by one of the pilots in an act of murder-suicide.

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“One of the pilots eliminated the other pilot and took the airplane to the ocean and intentionally ditched it,” Larry Vance, a former investigator with the Transportation Safety Board Canada, told Global News. “Somebody decided to end their own life and for whatever reason that everyone else was going to go with them.”

READ MORE: Malaysia Airlines Flight MH370 search ends with few answers after 3 years

For more than four years theories have swirled about what happened to the plane carrying 239 people that took off from Kuala Lumpur at 12:41 a.m. local time on March 8, 2014, before vanishing from radar roughly 40 minutes into the flight but continued flying for another six hours. Audio released by the Malaysian government revealed that the last words spoken were “good night Malaysian three seven zero.”

An exhaustive search of the Indian Ocean floor involving several countries failed to find the plane, but wreckage was discovered off the east coast of Africa.

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After studying detailed photographs of the debris, Vance and a team of international experts concluded the plane was deliberately crashed as sections of the flap system were in the downward position, meaning the plane entered the water at a relatively low speed.

“If the flaps were down, then somebody would have had to have put them down, and they had to have put them down intentionally,” said Vance, who is set to release his book, MH370 Mystery Solved, on May 23.

“I’m 100 per cent certain that evidence on the flaps show what we say they show.”

Canadian aviation expert Larry Vance appears on 60 Minutes Australia. (YouTube)

The plane was piloted by 53-year-old Capt. Zaharie Ahmad Shah and 27-year-old co-pilot Fariq Abdul Hamid. Vance could not say if it was the pilot or co-pilot who was the perpetrator or what the motivation was.

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Vance was interviewed along with other aviation experts as part of a 60 Minutes Australia episode that looked at whether the crash was intentional.

READ MORE: 2 plane parts to be examined in Australia for links to missing Malaysia Airlines Flight MH370

Simon Hardy, a Boeing 777 pilot and instructor, said that when the plane took a sudden 180-degree change of course, it flew along the border of Malaysia and Thailand, crossing in and out of each country’s airspace, to avoid detection.

“It’s going in and out of those two countries which is where their jurisdictions are,” Hardy said. “If you were to commission me to make [a plane] disappear I would do exactly the same thing.”

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Hardy said it was also clear this was a carefully planned course as the pilot Shah dipped his wing to see his hometown of Penang as a kind of “emotional goodbye.”

Vance told 60 Minutes he believes it was Shah who then turned off the lights in the passenger cabin and depressurized the airplane.

“That would be consistent with everything else that the pilot did,” Vance said. He believes it was at this time that Shah eliminated the co-pilot.

However, the theory proposed by Vance and other investigators is at odds with Australian air safety investigators, who believe the jet crashed into the water after it ran out of fuel and its pilots were incapacitated.

Martin Dolan, former head of the Australian Transport Safety Bureau, told 60 Minutes there was not enough evidence to support a murder-suicide conclusion.

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“The evidence is not yet sufficient to draw as firm a conclusion as you appear to have done,” Dolan said, adding that it was just speculation that the flaps were down and that the plane did not run out of fuel.

Although rare, there are previous cases of pilots intentionally crashing aircraft. In 1999, the co-pilot of EgyptAir Flight 990, Gamil el-Batouty, crashed a plane headed from New York-to-Cairo, killing 217 people. In March 2015, Andreas Lubitz, a Germanwings co-pilot, deliberately crashed his plane into the French Alps killing himself and 149 passengers.

“[The Malaysian Airline pilot’s] intention was to make the plane disappear forever, and make it so that no one would ever find it,” Vance said.

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