Until authorities know what happened to Malaysia Airlines Flight 370, they'll look for clues in the histories of everyone on board.
The cruel reality is that every one of the 239 people on board is both a possible victim and a possible suspect - until proved otherwise.
Already, some passengers and the pilots have fallen under increased scrutiny, and more are likely to come into focus as the search for answers continues.
CNN's Kate Bolduan spoke to the neighbor of co-pilot Fariq Ab Hamid to dig deeper.
Fariq Ab Hamid, 27, started at the airline in 2007 and has 2,763 flying hours.
Two vans were loaded with small bags, similar to shopping bags, at the home of the co-pilot, according to a CNN crew that observed activities at the residence.
It was unclear whether the bags were taken from the home, and police made no comment about their activities there.
U.S. intelligence officials are leaning toward the theory that "those in the cockpit" - the captain and co-pilot - were responsible for the mysterious disappearance, a U.S. official with direct knowledge of the latest thinking has told CNN.
The official emphasized that no final conclusions have been drawn and that all the internal intelligence discussions are based on preliminary assessments of what is known to date.
Acting Malaysian Transportation Minister Hishammuddin Hussein has told reporters the pilots didn't request to work together.