SEMPORNA - 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.
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.