Air crash investigators found evidence of a bird strike on a commercial jet that crashed in South Korea, killing 179 people on board. A preliminary report released by authorities Monday stated that both engines on the Jeju Air Boeing 737-800 jet contained duck DNA,

Duck remains were found in both engines of the Jeju passenger jet that crashed last month, killing 179 people in the worst air disaster in South Korea’s history.

The investigation into the deadliest air disaster on the country's soil remains ongoing, focusing on the role of bird strike and involving an analysis of the engines and the "localizer" landing guidance structure.

The exact cause of the Jeju Air crash remains unclear, and the investigation is complicated because the black boxes stopped recording four minutes before impact.

Pilots’ actions after that strike are an early focus of the investigation, according to people familiar with the probe.

South Korea released a preliminary report into last month’s deadly Jeju Air Co. crash that offers more detail on the role of bird strikes in the disaster, while still leaving crucial questions unanswered.