Forty days after Malaysia Airlines Flight 370 disappeared, neither a crash site nor wreckage have been discovered. As grief-stricken family members search for answers, several conspiracy theories are circulating.

After reports emerged saying that two of the flight's passengers boarded the plane with stolen passports, hijacking theories immediately began.

The passports were stolen from an Austrian man in 2012, and from an Italian man in 2013. Both men were traveling in Thailand when their passports were stolen.

Iranian friends Pouri Nour Mohammadi, 18, and Delavar Seyed Mohammad Reza, 29, somehow obtained the passports, used them to secure plane tickets, and successfully boarded the doomed flight.

After an investigation, Interpol officials ruled out the men being terrorists, stating that they were most likely seeking asylum.

Another well-publicized theory is that Flight 370's pilot, 53-year-old Zaharie Ahmad Shah, intentionally crashed the plane into the water.

Shah was allegedly extremely upset that his marriage was falling apart, and was also allegedly having problems with his girlfriend.

A friend of Shah's, who is also a pilot and did not want to be identified, stated that Shah was not fit to fly.

"He's one of the finest pilots around and I'm no medical expert," the friend told the New Zealand Herald, "but with all that was happening in his life, Zaharie was probably in no state of mind to be flying."

There are also reports that co-pilot Fariq Abdul Hamid tried to make a call from his cell phone while on the aircraft. It is against procedure for a pilot to have a personal electronic device turned on while in the cockpit.

Transport Minister Hishammuddin Hussein doubted reports that Hamid tried to make a call.

"If this did happen, we would have known about it earlier," Hussein told The New Straits Times.

Recent reports indicate that the co-pilot's cell phone was on, but it is unclear if a call was attempted.

Other theories include the plane being forced to land in Afghanistan, the passengers being held hostage on an island, the plane landing at a U.S. military base, and even the disappearance being an elaborate life insurance scam.

The Malaysian Police Chief Khalid Abu Bakar gave validity to the insurance scam theory in a news conference.

"Maybe somebody on the flight has bought a huge sum of insurance, who wants family to gain from it or somebody who has owed somebody so much money, you know, we are looking at all possibilities," he told reporters.

However, no evidence of an insurance scam or other explanation for the plane's disappearance have been confirmed.