BEIJING (AP) — A Beijing court began compensation hearings Monday morning for Chinese relatives of people who died on a Malaysia Airlines plane that disappeared in 2014 on a flight to Beijing, a case that remains shrouded in mystery after almost a decade.

Security was tight around the Chinese capital’s main Chaoyang District Intermediary Court and no detailed information was immediately available. Police checked the identities of journalists onsite and sequestered them in a cordoned-off area. Reporters were able to see relatives enter the court but were unable to speak with them before the hearing began.

Various theories have emerged about the fate of the plane, including mechanical failure, a hijacking attempt or a deliberate effort to scuttle it by those in the cockpit, but scant evidence has been found to show why the plane diverted from its original route from Kuala Lumpur to Beijing. The Boeing 777 with 227 passengers and 12 crew aboard is believed to have plunged into the Southern Ocean south of India but months of intense searching found no sign of where it went down and only fragments of the plane have washed up on beaches in the area.

Among the passengers onboard, 153 or 154 by differing accounts were citizens of China, causing the disaster to resonate especially in Beijing, where daily briefings and vigils were held for those missing. Some relatives refused to believe the plane had disappeared, believing it had been taken to an unknown site and that their loved ones remained alive, and refused a accept relatively small compassionate payments from the airline.

Details of the lawsuit remain cloudy, but appear to be based on the contention that the airline failed to take measures to locate the plane after it disappeared from air traffic control about 38 minutes after takeoff over the South China Sea on the night March 8, 2014.

Relatives have been communicating online and say the expect the hearings to extend to mid-December

Given the continuing mystery surrounding the case, it remains unclear what financial obligations the airline may have and no charges have been brought against the flight crew. However, relatives say they wish for some compensation for a disaster that deprived them of their loved ones and placed them in financial difficulty.

China’s largely opaque legal system offers wide latitude for judges to issue legal or financial penalties when criminal penalties cannot be brought.

Similar cases brought in the U.S. against the airline, its holding company and insurer have been dismissed on the basis that such matters should be handled by the Malaysian legal system.

China itself says it is still investigating the cause of the crash of a China Eastern Airlines jetliner that killed 132 people on March 21, 2022. The disaster was a rare failure for a Chinese airline industry that dramatically improved safety following deadly crashes in the 1990s.

The Boeing 737-800 en route from Kunming in the southwest to Guangzhou, near Hong Kong, went into a nosedive from 8,800 meters (29,000 feet), appeared to recover and then slammed into a mountainside.