Dulmatin had received training in al-Qaeda camps in Afghanistan. He is believed to have been the protégé of Azahari Husin and under Azahari's guidance Dulmatin became an electronics specialist and bomb making expert. He is allegedly one of the masterminds behind the 2002 Bali bombings in Indonesia which killed 202 people, including seven U.S. citizens and 88 Australians. Working alongside Azahari, Dulmatin helped to assemble car bomb and explosive vests used in the attack. He allegedly set off one of the bombs with a mobile phone.
He is believed to be with the Abu Sayyaf group in the Philippines since 2003 and was involved in providing explosive expertise and training other militants. From radio intercept and human intelligence, authorities believe that Dulmatin was wounded in a gun battle with the Philippines military in January 2007, on the southern island of Jolo. In May 2007, Dulmatin again eluded capture when he fled from a safe house in Simunul island just hours before Philippine police and military forces raided the location. The authorities found 4 children believed to be Dulmatin's children.
The United States government has offered a reward of up to $10 Million for the capture of Dulmatin under the Rewards For Justice Program.
On 19 February, 2008, Philippine authorities announced that the dead body of a man, believed to be Dulmatin, had been found in a grave in the southern province of Tawi-Tawi. Further DNA testing is expected to confirm whether the body is that of Dulmatin.