When a lonely and impressionable teenager became fixated on Islamic State, police began an operation that ended up further radicalising him. At just 14, the boy was then charged with terrorism offences. Courts and justice reporter Nino Bucci tells Patrick Keneally how and why police targeted the vulnerable teenager, and the questions the case raises about the authorities’ role in the deradicalisation process You can support the Guardian at theguardian.com/fullstorysupport