Malaysia's prime minister says the disappearance of Malaysia Airlines Flight 370 appears to be deliberate." The latest evidence suggests the plane didn't experience a catastrophic incident over the South China Sea as was initially suspected. Prime Minister Najib Razak said the investigation has refocused onto the crew and passengers aboard the missing plane. He added that ... all possibilities are still being investigated. A Malaysian government official who is involved in the investigation said investigators have concluded that one of the pilots or someone else with flying experience hijacked the missing Malaysia Airlines jet. The official said that hijacking was no longer a theory. "It is conclusive." A Malaysian official, who also declined to be identified because he is not authorized to brief the media, said only a skilled aviator could navigate the plane the way it was flown after its last confirmed location over the South China Sea. The official said it had been established with a "more than 50 percent" degree of certainty that military radar had picked up the missing plane after it dropped off civilian radar. Malaysian officials have said radar data suggest it may have turned back and crossed back over the Malaysian peninsula westward, after setting out toward the Chinese capital. The flight altered its course more than once after it lost contact with ground control and that it made significant changes in altitude. Investigators say there's further evidence suggesting the jet did not crash immediately after being lost on radar; a transmitter on the plane tried for another four hours to ping satellites.