The attacks bear the hallmarks of the active terrorist network Jemaah Islamiah ( JI ) , which is believed to be responsible for several bombings in Indonesia , including the 2002 Bali nightclub bombing , the 2003 Marriott Hotel bombing and the 2004 Australian Embassy bombing . Rohan Gunaratna , head of terrorism research at Singapore 's Institute of Defence and Strategic Studies , told Agence France-Presse that " The only group that has the intention and capability to mount a coordinated and simultaneous attack against a western target in Indonesia is Jemaah Islamiyah . " Although a link to JI has not been confirmed , the bombings were quickly condemned as terrorist attacks by the authorities . Police Major General Ansyaad Mbai , a top Indonesian anti-terrorism official , told the Associated Press that the bombings " were clearly the work of terrorists " . Major General Mbai identified Malaysian men , already wanted in connection to previous bombings in Indonesia , as the suspected masterminds of the attacks . The chief suspect was Azahari Husin , a member of JI who was an engineering expert and former academic with a doctorate from University of Reading ( late 1980s ) . Husin was nicknamed the " Demolition Man " and was thought to have collaborated with the second suspect : Noordin Mohammed Top , a bomb maker whose wife was sentenced to three years in prison for harbouring him . Azahari was killed in a police raid in November 2005 , while Noordin " has been killed after a lengthy and violent siege , Indonesia 's police chief said " by " heavily armed counter-terrorism police " on 16 September 2009
2003 Marriott Hotel bombing
2003 Marriott Hotel bombing
2005 Bali bombings