A month before Malaysia Airlines Flight MH370 vanished over the Indian Ocean — less than an hour into its flight — Captain Zaharie Ahmad Shah made a 45-minute phone call that has puzzled investigators for years.

It was later revealed the February 2, 2014 phone call was between the esteemed Malaysia Airlines pilot and his first cousin and aircraft engineer Zulhaimi Bin Wahidin.

Both men had worked for Malaysia Airlines for decades when the Boeing 777 jet with 239 people on board vanished on March 8, 2014 during a routine flight from Kuala Lumpur in the world's greatest aviation mystery.

Former Malaysia Airlines engineer Zulhaimi Bin Wahidin. Photo / Facebook

Speaking to The Australian, Zulhaimi insisted his cousin was innocent and lashed out at suggestions he had provided the pilot with technical information that would've given him the ability to hijack the aircraft.

Zulhaimi was interrogated by police on numerous occasions with investigators initially being suspicious of the aircraft engineer.

"I was at police headquarters for three days. It spanned from morning to evening," Zulhaimi told the publication.

"I told them that Zaharie is a smart guy. He doesn't need me to get all of the information."

Investigators backed off Zulhaimi after he showed them his phone records, revealing he and his cousin spoke regularly over the past 20 years.

MH370 is still missing despite years of investigations.

An official report released in July last year, following a lengthy investigation and a long-running fruitless $144.8 million search, gave no new clues about why the plane disappeared, sparking anger among relatives.

The last known location of MH370

Malaysia's new government, which took power in May last year, has said the search could be resumed but only if new and compelling evidence came to light.

Zulhaimi told the publication "of course" his cousin was innocent and admitted he had spent the past five years feeling "uneasy" about the pilot's "name being tarnished".

"They're trying to blame him for what happened and it's very hard for me to swallow that because he's not that kind of a person," he told The Australian .

Zulhaimi landed on police radar almost immediately after MH370 went missing in 2014 after investigators received data the aircraft engineer had tried to call his cousin after the plane went down.

Experts also called on Zulhaimi to explain the degree of his technical knowledge as part of the investigation, fuelling even more suspicion.

"He was around the neighbourhood, around my area, so he dropped by to see my kids," Zulhaimi said, recalling the last time he had seen his cousin alive.

"Just to say hello. We chitchat for a while, about half an hour or one hour.

"He was a normal, jovial guy. I didn't anticipate that some bad thing was going to happen. It was a big shock to me as well."

Zulhaimi said the past five years has been difficult for the family as they came to terms with the pilot's death.

"The whole family has tried to forget about it," he said. "We just accept the fact that he's dead by now, I think."

It's not the first time Captain Shah's phone has been in the spotlight.

Recently it was revealed the married captain sent more than 90 online messages to twin models Lan Qi Hui and Qi Min, begging them to visit him in Kuala Lumpur.

MH370 Captain Zaharie Ahmad Shah.

The Sun reported how Shah plagued the young Instagram model twins, 26, with creepy messages before his plane's mysterious disappearance four years ago.

Now Qi Min Lan has told the Gold Coast Bulletin that the police spoke to her about Zaharie after his plane went missing.

"Police know I dunno (sic) him at all. He just a social network's fan of mine," she said in an email to the paper.

"I have many followers in my social network he just one of them. Anyhow the pilot no disturb my life because I no reply him at all."

His 97 Facebook messages have been revealed as psychologists claim he was "self-destructive".

The father-of-three was co-pilot of MH370, which mysteriously vanished carrying 238 passengers and crew in March 2014.
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He sent the Malaysian twin sisters sexually suggestive messages.

A photo from model Qi Min Lan's facebook page. Photo / Facebook

On one occasion he commented under a picture of Qi Min Lan in a bathrobe with the comment: "Just showered?"

He repeatedly asked the girls when they were coming to his hometown, despite being ignored.

Zaharie also used his Facebook to call Malaysian prime minister Najib Razak a "moron".

He also slammed the government which owned the airline he flew for.

Zaharie urged his followers: "There is a rebel in each and every one of us. Let it out!"

Aviation expert Geoffrey Thomas said he should have been fired for his political rants

He told Daily Telegraph: "It should have raised serious alarm bells with the airline that you have someone flying who has such strong anti-government views.

"If a Qantas pilot did something like that, he would be spoken to and grounded."

Four years on, experts are no closer to finding the missing Boeing 777. Here's what we know.

Zaharie, a passionate cook and keen fisherman, Shah lived with his wife in a luxury gated community where he was said to have built his own flight simulator.

In the wake of the plane's disappearance, rumours surfaced claiming his wife had moved out of their home.