viv41 - //Shouldn't have shot him, should have been tranqualised. //
This was debated earlier on the thread - tranquilising was not an option because it does not have an instant effect on an animal of that size, and the worry was that as it took effect, it may have enraged the gorilla and caused him to harm the child.
Although experts in primate behaviour are saying that the gorilla was protecting the child, and its action in pulling him along the moat was motivated by his distress at all the noise and screaming from the crowd, I still believe that the risk of a sudden change of behaviour was too big a risk to take, and sadly the action taken was the only viable - if very difficult - choice.