I'm not strongly convinced of his innocence, I'm just on the fence. However, I'll answer your question anyway - the speed at which everything moved can be read two ways. It could be a sign of very convincing evidence, or it could be a sign that the police have rushed to judgement. This is a high profile case where public and media pressure to solve it is intense. Its also a heartwrenching case, where the victim is an innocent and very vulnerable little girl.
The police are human beings, both their common human decency and their professional pride can feed into a rush to judgement against the wrong suspect in cases like this. Or, they might have absolutely solid evidence that we know nothing about. I've seen both happen, and IMO that's why you're seeing very divided opinions in this thread.