A 12-year-old Pakistani boy says he killed a 10-year-old fellow pupil to close a religious school in order to stop sexual abuse by a teacher.
The boy was arrested in the city of Multan, in Punjab province, on Friday.
The boy said he had "no bad feelings" about his victim and that he knew of up to 10 boys who had been abused. Police are looking for the teacher named.
Rights activists have recently stepped up calls for investigations into abuses at religious schools.
The 12-year-old boy was brought before a police press conference in Multan on Saturday, saying he slit the throat of the younger boy in a school bathroom.
"I had no bad feelings against this boy. I was obsessed with getting this school closed," he said.
"I wanted to give a bad name to the school so that the abuse of children could stop."
Multan police chief Munir Ahmed Chisti said the boy could face life imprisonment if found guilty. Juveniles cannot be executed under Pakistani law.
Human rights activists want more investigations into abuses in madrassas, but the subject is considered taboo in highly conservative Muslim society.