SEOUL, South Korea (AP) — Families of victims of December's devastating plane crash in South Korea have filed a complaint against 15 people including the transport minister and the airline chief who they believe are responsible for the disaster that killed all but two of the 181 people on board.

Police and government officials have already been investigating the Jeju Air crash, so the complaint is largely seen as a symbolic step calling for a swifter and more thorough probe. Many bereaved families complain of what they see as a lack of meaningful progress in efforts to determine what caused the disaster and who is responsible.

On Tuesday, 72 bereaved relatives submitted the complaint to the Jeonnam Provincial Police agency in southern South Korea, according to their lawyers and police.

The 15 people cited in the complaint include the transport minister, Jeju Air's president and airline officials handling maintenance and safety issues, along with officials at Muan International Airport who are responsible for preventing bird strikes, air traffic control and facility management, according to a statement from a lawyers' group supporting the relatives.

"Four months after the disaster, we can't help feeling deep anger and despair over the fact that there has been little progress" in the investigation, Kim Dae-hye, a bereaved family member, said in the statement.

Lawyer Lee So-Ah said Wednesday the complaint would formally require police to brief bereaved families of their investigation, though police have so far only voluntarily done so.

The Boeing 737-800 operated by Jeju Air skidded off the runaway at the Muan airport on Dec. 29 after its landing gear failed to deploy, slamming into a concrete structure and bursting into flames.

Authorities have since said they found traces of bird strike in the plane's engines and that the plane's two black boxes stopped recording about 4 minutes before the crash. Many analysts said the concrete structure, which housed a set of antennas called a localizer that guides aircraft during landings, should have been built with lighter materials that could break more easily upon impact.

But no exact cause of the crash has been announced and no one has been legally persecuted yet over the crash, the country's deadliest aviation disaster since 1997.

Jeonnam Provincial Police agency officials said they've been investigating the accident. They suggested a complex incident like the Jeju Air crash would require a lengthy investigation but declined to say when they expect to wrap up their probe.