“My sister was always caring towards other people and taught her children to be compassionate,” Daud Samari, Djumani’s younger brother, told reporters.
The church bombing family were in the same religious study group as the Surabaya police station bombers and a third family believed to be linked to the wave of attacks, authorities said.
“They had the same teacher and they regularly met for Koran recital every week,” said East Java police chief Machfud Arifin.
The coordinated church attack was a sign local extremist groups were becoming more proficient, and stirs concerns about an uptick in extremism as hundreds of Indonesians who flocked to fight alongside Isil in the Middle East return home.
“They were better organised…and suggests a higher level of capacity than what we have seen in recent years,” said Sidney Jones, director of Jakarta-based Institute of Policy Analysis for Conflict.
The families have been linked to the local chapter of Indonesian extremist network Jamaah Ansharut Daulah (JAD), which police said was behind the attacks.
The radical group supports Islamic State, whose ambitions have been curbed after losing most of the land it once occupied in Iraq and Syria.