Two large oil slicks, between six and nine miles long, consistent with a downed jetliner were found on Saturday, and the following day Vietnam’s Civil Aviation Authority published a picture of what could have been an aircraft door on its Web site, found in roughly the right area, between Malaysia and Vietnam.  But it said it was too dark to be sure and that more aircraft and planes from both countries would be dispatched to investigate in the morning. Vietnamese media also reported that another piece of debris had been found that might have been part of the plane’s tail.  Some 40 ships and 34 planes from eight nations, including the United States, expanded their search for the plane on Sunday over a vast area of the ocean. After insisting for 24 hours that investigations were continuing, Malaysia Airlines acknowledged on Sunday that it was “fearing the worst.”  The mystery surrounding the disappearance of Malaysia Airlines Flight MH370 thickened Sunday after investigators said the plane appeared to turn around before vanishing from radar screens, and as authorities examined closed-circuit television footage of at least two passengers, apparently traveling together with stolen passports.  The information about the suspect passengers has led to speculation that terrorists might have downed the flight , a red-eye carrying passengers from Kuala Lumpur, Malaysia, to Beijing that vanished from radar after midnight Saturday (Friday afternoon Eastern time).  The fact that the plane was cruising at steady altitude in decent weather, and apparently did not emit a distress signal before disappearing, also were possible indications of a sudden catastrophic event striking the plane.  “I think this is a criminal act of some kind,” said Scott Hamilton, an aviation expert and founder of Leeham News in Seattle. “If both engines had failed, the pilots would have had plenty of time to call and say, ‘We have a problem.’ ”  Malaysian investigators narrowed their focus Sunday on the possibility that the plane may have disintegrated in mid-flight, according to the Reuters news agency.  If the plane had broken up on impact with water, search teams would have been expected to find a fairly concentrated pattern of debris, officials said. But they said an explosion was not the only possible cause: The plane, a Boeing 777-200, could have broken up due to mechanical issues.  The plane, which was more than 11 years old, had suffered damage to its wing after a minor collision with another aircraft in 2012 but had been fully repaired.  Hamilton said possibilities included a bomb, passengers penetrating the cockpit and seizing control of the plane or pilot suicide.  But Deputy National Security Adviser Tony Blinken told CNN that it was too early to say if foul play was involved and premature to speculate on whether the passengers with stolen passports had a role to play.  European officials indicated on Saturday that two of the people on board were using passports that had been stolen in Thailand within the past two years.  Luigi Maraldi, 37, from Italy and Christian Kozel, 30, from Austria had initially been listed as among the plane’s passengers, but both men were subsequently found to be safe.  Flight booking information accessed through the KLM Web site showed the passengers had adjacent ticket numbers, and were both booked on a subsequent flight from Beijing to Amsterdam. One, traveling under Maraldi’s name, was due to proceed to Copenhagen, and the other to Frankfurt, Germany.  Their itinerary was separately confirmed by an employee of China Southern Airlines, which was a codeshare partner on the flights and had sold them the tickets.  Reuters reported that people presenting themselves as the two men had booked their tickets together at a travel agency in Pattaya, Thailand. Thai media reported that Maraldi had lost his passport in Phuket last year; he surrendered it at a motorcycle rental shop and another man had collected it.  On Sunday, Malaysia’s transportation minister Hishammuddin Hussein said that Malaysian intelligence officials also were checking the identities of two other passengers, according to the Associated Press.  “All the four names are with me and have been given to our intelligence agencies,” Hishammuddin said, according to AP. “We do not want to target only the four; we are investigating the whole passenger manifest. We are looking at all possibilities.”  Later, however, the director of Malaysia’s Department of Civil Aviation said there were only two men with false passports and that authorities were checking closed-circuit television footage of them. “We have the CCTV recordings of those passengers from check-in right through the departure point,” he said, according to Bloomberg News. “These records of CCTV are now being used for investigation of this matter.”  Adding to the confusion, Malaysia said on Sunday that the flight might have turned back from its scheduled route to Beijing before disappearing.  “What we have done is actually look into the recording on the radar that we have and we realized there is a possibility the aircraft did make a turnback,” Rodzali Daud, the Royal Malaysian Air Force chief, told reporters at a news conference, according to Reuters.  Malaysia said it had now expanded its search to the country’s western coast, the opposite side of the peninsula from the plane’s last sighting.  “The outcome so far is there is no sign of the aircraft,” Malaysian civil aviation chief Azharuddin Abdul Rahman said, according to Reuters.  “On the possibility of hijack, we are not ruling out any possibility,” he told reporters.  But it nevertheless appeared implausible that a passenger plane could simply disappear from radar screens over the ocean unless it had crashed, experts said.  “It can’t vanish from primary radar unless it is a stealth bomber,” said Mikael Robertsson of FlightRadar24, a flight-tracking service.  The airline’s own transponder, which broadcasts the plane’s position and location, went completely dark while the plane was cruising at a steady 35,000 feet. “Everything indicates it must have lost altitude suddenly,” he said.  The National Transportation Safety Board said Saturday night in Washington that a team of investigators was en route from the United States to Asia to assist with the investigation. U.S. officials said Sunday that intelligence agencies were examining the possibility of a connection to terrorism.  Asked earlier whether terrorism was suspected in the plane’s disappearance, Malaysian Prime Minister Najib Razak said authorities were “looking at all possibilities, but it is too early to make any conclusive remarks.”  Nevertheless, he said airport security procedures were being reviewed.  “We will enhance them if necessary, because we still do not know the cause of the incident,” he told reporters, according to Reuters.  International police agency Interpol confirmed Sunday that the two stolen passports were on its database, but said no country had made what should be routine checks about them.  “Whilst it is too soon to speculate about any connection between these stolen passports and the missing plane, it is clearly of great concern that any passenger was able to board an international flight using a stolen passport listed in Interpol’s databases,” Interpol Secretary General Ronald Noble said in a statement.  Noble expressed frustration that few of Interpol’s 190 member countries “systematically” search the database to determine whether documents being used to board a plane are registered as lost or stolen.  “This is a situation we had hoped never to see. For years Interpol has asked why should countries wait for a tragedy to put prudent security measures in place at borders and boarding gates,” he said.  Nevertheless, Clive Williams, a counter-terrorism expert at Australia’s Macquarie University, said it seemed unlikely that terrorists would target a Malaysia Airlines flight. Data from Interpol data shows there were 39 million lost or stolen passports as at the end of last year.  “The stolen passports may or may not be related but more likely not,” he wrote in an email. “I think it likely that most Asian flights have passengers with stolen passports on board.”  The plane carried passengers from 14 countries, including three Americans, according to the manifest posted on the airline’s Web site. They were identified as Philip Wood, 51, an IBM employee working in Malaysia; Nicole Meng, 4; and Yan Zhang, 2.  Austin-based Freescale Semiconductor confirmed Saturday that 20 of its employees were aboard the plane. Twelve are from Malaysia and eight are from China, the firm’s president and chief executive, Gregg Lowe, said in a statement.  “At present, we are solely focused on our employees and their families,” Lowe said. “Our thoughts and prayers are with those affected by this tragic event.”  Flight MH370 lost contact with Malaysian air traffic control at 1:20 a.m. Saturday (12:20 p.m. EST Friday), less than an hour after taking off from Kuala Lumpur and as it was completing its ascent. It vanished on the border of the territorial waters of Malaysia and Vietnam, where the Gulf of Thailand meets the South China Sea. It had been due to land in Beijing at 6:30 a.m. Saturday (5:30 p.m. EST Friday).  The airline said it would establish a command center either in Kota Bharu, Malaysia, or Ho Chi Minh City, Vietnam, as soon as the location of the aircraft is established. A 94-person caregiver team was providing emotional support for families in Malaysia and a similar size team in Beijing, the airline said.  But in China, frustration has steadily grown among relatives at the lack of news; on Sunday, some threw water bottles at the airline team when they arrived to share information on the flight.  The plane’s sudden disappearance without a call for help brought back memories of an Air France flight that disappeared over the Atlantic Ocean en route from Rio de Janeiro to Paris on June 1, 2009.  While some wreckage and bodies were found in subsequent weeks, it took nearly two years for the main wreckage and the plane’s flight recorders to be recovered. The final report said that pilot errors in responding to technical problems led to the crash.  Barnes reported from Washington. Harlan reported from Seoul. Liu Liu, Gu Jinglu and Xu Jing in Beijing and Karen DeYoung, Ian R. Shapira and Sean Sullivan in Washington contributed to this report.
Vietnam posts image of what could be a plane’s door on Web site; search continues for airliner with 239 aboard.