The Malaysian police in charge of finding out what happened to Malaysia Airlines Flight 370 admitted on Wednesday something the world is beginning to fear: we may never really know what happened to the doomed jetliner and the 239 people on board.

Speaking to reporters in Kuala Lumpur, Inspector General Khalid Abu Bakar said, "Investigations may go on and on and on. We have to clear every little thing. At the end of the investigations, we may not even know the real cause. We may not even know the reason for this incident."

Malaysia's police have concluded their investigation into the 227 passengers on board the plane and have cleared them all of suspicion. The plane's crew, including senior pilot Zaharie Ahmad Shah, 53 and his co-pilot Fariq Abdul Hamid, 27, continue to be under investigation, with Shah's flight simulator being pored over by the FBI. The probe is now focused on possibilities that include a hijacking, sabotage or psychological problems among those employed by Malaysia Airlines, The Sydney Morning Herald reports. They're even looking into the plane's food to somehow ensure that it wasn't poisoned.

Inspector General Khalid Abu Bakar told reporters there was more — but he couldn't say due to the ongoing criminal investigation.

“I’m sorry, there are things we cannot reveal to you … not that I don’t want to reveal to you, but we cannot do that because it’s a criminal investigation, ongoing,” he said. “We have not concluded the whole thing and we are still awaiting reports from experts overseas and internally. Who knows, maybe there will be prosecution later on. So this will affect the prosecution’s case, if we start revealing our findings."

It's been three weeks since the Boeing 777 disappeared less than one hour after taking off from Kuala Lumpur International Airport, bound for Beijing. The pilot signed off, saying, "Good night Malaysian 370," shortly before somebody on board deliberately turned off the plane's transponder. Authorities have concluded that the plane's journey ended seven hours later somewhere in the southern Indian Ocean, and there were no survivors — but they have yet to find any debris.