Two Vietnamese sailors detained on charges of stabbing to death the Korean captain and the chief engineer of their fishing boat arrived in Korea late Thursday for questioning.

The focus of the investigation is expected to uncover the motive behind the killing, which happened aboard fishing boat Kwang Hyun 803 last Monday in the Indian Ocean.

The suspects, two 32-year-old men, were taken into custody at the Port of Victoria in Seychelles on Tuesday night. Seven officials from the Korea Coast Guard had boarded the vessel to prevent the possible escape of the suspects.

The men were to be sent off to the headquarters of the Busan Coast Guard later in the day, as the officials have grilled key witnesses including three sailors and a Korean navigator surnamed Lee from Kwang Hyun 803.

Lee had testified that the Vietnamese sailors shared bottles of liquor before the stabbing occurred.

The two sailors reportedly had unfriendly relations with the victims.

Authorities are scheduled to conduct 10 days of investigation before forwarding the case to prosecutors.

The victims’ bodies are expected to arrive at Korea on Friday by air transport, and will be handed over to the bereaved families after autopsies and other necessary procedures related to the investigation.

By Yoon Min-sik (minsikyoon@heraldcorp.com)