Could the terrorist attack on Berlin's Pride celebrations, allegedly by a 21-year-old Islamist, have been prevented? This question has been the subject of debate driven largely by the fact that the young German man — born in Germany in 2005 to parents of Lebanese origin — had been convicted and released just weeks before the attack.

Abdul Ballout, who drove his car into a crowd in Berlin's Tiergarten park — killing one woman and injuring 31 people, some seriously — had set out last year intending to join the so-called "Islamic State" (IS) terrorist group in Syria. However, he was arrested en route in Lebanon, detained there and subsequently deported to Germany.

Back in Germany, he stood trial on charges of preparing a serious act of violence endangering the state. He was found guilty and sentenced in mid-May to 22 months in prison, but this sentence was initially suspended. He was released — and attacked Berlin Pride just weeks later. The day after the incident, he was shot dead by police while they were attempting to arrest him.Police 'should have kept an eye on' Berlin Pride attackerTo view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video