Authorities have detained a suspect over the May 19 bomb blast outside a school in southern Italy which killed a 16-year-old girl.
Prosecutor Cataldo Motta said that police are holding a 68-year-old man who allegedly held a grudge against the judicial system as a suspect in the Brindisi bombing.
But Mr Motta added they are not entirely convinced about his motive and that the investigation is continuing.
The blast killed Melissa Bassi and wounded four other students.
Authorities originally suspected terrorists or organised crime were behind the blast.