Decisions in cases such as this are not made lightly or without the best investigation possible.

I can't speak to the quality of these sort of investigations in the UK, but I (and Ivonne) can testify in detail to the sort of work that epitomizes them in both Florida and Ohio--

They are often beneath contempt.

-- The time and funds expended are almost always inadequate, and relate powerfully to the skin color and socioeconomic position of the victim and the accused.

-- As has been stated (correctly), the pay scales for investigative personnel are so poor that it is hard to fill the positions at all, let alone with competent people.

-- Emotional numbness is the only defense possible (other than a different job) for a case worker with a workload so huge that real justice is a bad joke.

Because of the above, these positions tend to select for people who can (or who already have) adopted that detached position. When hiring young social workers to fill such nightmare jobs, one has the feeling of being an emotional executioner.

A good friend of mine is a PhD psychologist with the  state of Florida, who has made it his business to represent the interests of the child in such cases. He must not become involved in the whole question of justice as it applies to the defendant or the parents, but seek only the best for the child. Considering the quality of the investigative work and the "justice" of the results in the  courts, he has told me that this detachment is very, very hard.  

Capitalism searches out the darkest corners of human potential, and mainlines them.