SEMPORNA (THE STAR/ASIA NEWS NETWORK) - The father was a notorious pirate before his death in the late 1990s.
Muktadir, a Filipino, terrorised the Sulu and Celebes seas separating Sabah and the southern Philippines.
His five sons, known as the "Muktadir brothers", are part of a well-armed family of kidnappers believed to be behind the kidnapping of tourists from Taiwan and China, among others.
Malaysian security forces are hunting them down as they believe the brothers are behind the last four cross-border kidnappings in the east coast of Sabah since November.
Sabah CID chief Sr Asst Comm Omar Mammah said the police believed the same group was involved in all four abductions over the past seven months. However, he did not disclose the identity of the kidnap-for-ransom (KFR) group.
According to intelligence officers interviewed by Sunday Star, the Muktadir brothers are one of the most active of the 14 known KFR groups in the southern Philippines.
Unlike the Muktadir brothers, the other KFR groups operate within the Philippine waters.
Malaysian security forces have identified three of the brothers as Nelson, Badung and Gadafi, while two others use the names Murphy Ambang Ladia alias Gulam and Ali, who is also known as Braun.
The brothers are beleived to be based in a water village in Sitangkai island in the Tawi Tawi chain of islands that straddles Sabah's east coast, The Sunday Star reported.
It said the brothers were linked with cross-border smugglers and owned numerous speed boats and a cache of weapons that make them a feared clan in the southern Philippines.