Abu Sayyaf

All seven men arrived in Malaysia in September 2015 through the town of Sandakan in the state of Sabah

The Abu Sayyaf Group is known to behead its hostages unless ransom payments are made

Troops killed six members of the IS-linked group during a firefight on the tourist island of Bohol

A video reposted by the militancy-monitoring group SITE showed a machete-wielding militant kill the hostage

Tugboat was in waters off east coast of Sabah when it was attacked by armed men in a white boat, say police

From remote jungle bases on Jolo and Basilan islands loosely organised group roams on fast boats to snatch hostages