Pirates KILL CAPTAIN But Don't Hijack Ship?

 This story seems a bit confusing. Pirates apparently killed the captain of a ship, but didn't try to hijack it? According ro the article below, the pirate attack occurred early in the morning at about 3am in international waters when the ship was returning to the UAE from Iran carrying petroleum products, but there was no attempt to hijack the vessel. Does that seems suspicious?
    . . . June


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Gulf pirates killed captain but didn't hijack ship
Emirates24|7:

The body of the Sri Lankan captain killed aboard the UAE based tanker Ocean Trite will be released on Wednesday, said the owner of the vessel.

“Nine crew members, who are in police custody for interrogation will also be released today,” said Syed Hassan, the owner of Alco Shipping that owns the vessel.

Speaking to Emirates 24|7 last evening, Hassan said that the remaining crewmen are being released, “because the police have established it as a pirate attack.”

Sunil Dharmaratne was captaining the vessel Ocean Trite along with seven other Sri Lankans and two Indian nationals.

“The pirate attack occurred early in the morning at about 3am in international waters when the ship was returning to the UAE from Iran carrying petroleum products,” he added. According to sources there was no attempt to hijack the vessel.

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