The disappearance of Malaysia Airlines Flight 370 has baffled investigators for more than four years, but a pair of retired Canadian air crash investigators believe they’ve found the answer.

On March 8, 2014, the passenger jet carrying 239 people was travelling from Kuala Lumpur to Beijing but crashed somewhere in the Indian Ocean.

After years of analyzing wreckage photos, Larry Vance and Terry Healsep, retired members of the Canadian Transportation Safety Board from Ottawa, allege the crash is part of a mass murder-suicide perpetrated by one of the pilots.

"The evidence points the fact that this pilot decided that, for whatever reason, he wanted this airplane to disappear,” Vance told CTV News on Monday.

Their theory contradicts that of Malaysian officials who believe the Boeing 777 ran out of jet fuel and nosedived into the ocean.

Vance and Healsep believe the large chucks of debris that washed up in Africa would not have survived a freefall from the sky. Instead, they say the pilot intentionally slowed the plane down before hitting the water.

"The last five or six seconds, the aircraft had to have come in down at a very low speed, with the flaps down, under control and in a ditching configuration,” Healsep said.

They believe the pilot likely quickly killed the passengers by depressurizing the cabin, which could explain why there were no distressing texts, no emergency phone calls and no mayday alerts coming from the plane before it disappeared.

The retired investigators also believe the pilot then took the plane to a distant part of the Indian Ocean before landing in the water.

"If a pilot takes a plane intentionally to the ocean and configures it and ditches it in a place where he knew there could be no survival -- for him or the passengers -- then that's a criminal act,” said Vance. “We would call that murder."

The pair won’t speculate on a motive behind the alleged murder-suicide, but believe investigators are working with a flawed conclusion, making it harder to find the aircraft.

Malaysian authorities have not commented on Vance and Healsep’s theory.

They are publishing a book on the subject titled MH370: Mystery Solved on May 23.

With a report from CTV News’ Glen McGregor