Jakarta school mosque blast suspect's diary reveals loneliness behind attack that injured 96

The teenager suspected to be behind the bomb attack at a school mosque had been spiralling into isolation for months, as revealed by his 42-page diary. The Indonesian students, as per reports, had soaked up extremist material from a Telegram group that glorified white supremacist violence. New details from investigators sketch a picture of a 17-year-old who felt cut off from the world and tried to find belonging in a Telegram group that praised mass killers. Here's what we know.

Loneliness led to terrorist activity?

The attack took place in early November during Friday prayers. Four small bombs exploded in the courtyard, injuring 96 people and leaving shoes, prayer mats and shards of glass scattered across the ground. Another three devices failed to detonate. Police say the student built all seven bombs at home, following YouTube tutorials and ordering materials like potassium chloride and nails through online marketplaces without raising any flags.

Jakarta police spokesperson Reonald Simanjuntak told Reuters that the teenager acted alone. "He wanted to be recognised by members of the online community … because he feels lonely," he said, adding that the 17-year-old is being treated as a "child facing the law" under the nation's juvenile crime regulations and has not been formally identified. "There was no place for him to express himself, his emotions, to his family or to his friends. A relative told Reuters he rarely spoke to anyone and spent most of his days on his laptop.

"Diary Reb"

During a raid on his home, investigators found a 42-page notebook titled Diary Reb, which they say refers to a personal "diary of struggle". It had sketches of the mosque layout, notes on where to place the explosives, and the date November 7 written by hand. Police believe he chose Friday prayers to hit the largest possible crowd. The diary also included reflections on past trauma and wrote about taking his own life, along with harming others. However, he survived the attack because a device meant to kill him did not fully explode. He is recovering in the hospital and will soon be questioned.

The teenager had also been active on an international Telegram channel, where users shared violent content and discussed attacks like the Christchurch mosque shootings and the Columbine killings. Telegram said such content violates its rules and that its systems remove millions of pieces of violent material daily. Google has not commented on how the bomb-making videos stayed up on YouTube.