Police believe the gunmen who shot dead a Taiwanese tourist and kidnapped his wife on Pom Pom Island off Sabah have links to the Abu Sayyaf group.
Inspector-General of Police Khalid Abu Bakar said on Saturday that the militant organisation is notorious for ransom kidnapping, though no demands have been made for the safe return of Madam An Wei Chang, 58.
Her husband, Mr Lin Min Hsu, 57, was shot dead by the group at a chalet around 1am on Friday.
He was found lying on the floor with wounds to his chest after the authorities responded to a report of gunshots being fired. Mr Khalid told The Star: "The initial information we have is that there were eight of them.
"They were a band of opportunists who took advantage of the security void left by Filipino authorities which had been redeployed to concentrate on the Haiyan disaster."
He also did not rule out the involvement of locals in planning the raid, saying police were investigating if these individuals were Sabahans or Filipinos.
He said: "The Eastern Sabah Security Command (Esscom) is still new. People have to understand that it is a very wide area of 1,400km to cover and we can't be everywhere at once.
"These men planned a hit-and-run raid which has made it hard for us to track them."
Esscom was set up after the Feb 12 Sulu intrusion into the Sabah town of Lahad Datu.
A massive sea and air search has been launched to locate Madam An and the gunmen.
Mr Khalid said Malaysian authorities had stepped up security in Semporna, Sandakan and Tawau, and was combing eastern Sabah waters for the suspects and the victim.
He said: "I hope that she (Madam An) is not in Filipino waters. We have contacted the Filipino border authorities to help with the search effort.
"We are also sweeping our side as well to ensure that the suspects are not using our territory to hide the victim."
Meanwhile, other guests at the resort were seen snorkelling and lazing on the shore, oblivious to Friday's shooting and the tight security cordon put up.
In the aftermath of the killing, Taiwan's Ministry of Foreign Affairs issued an "orange" travel alert for the eastern coast of Sabah.
It urged the public to avoid travelling to the area unless necessary, the Focus Taiwan website reported.
Under the ministry's four-colour-coded travel advisory system, the "orange" alert is the second highest level.
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