Complex sentence: He passes his imagined conclusions on to the police, who also misread the intentions of the young man, and shoot him dead to "protect" the child, who they think is in danger.
Split into simpler sentences: He passes his imagined conclusions on to the police, who also misread the intentions of the young man. However, at this point, the police arrive and shoot him dead to "protect" the child, who they think is in danger.