This should be the case, and as sibling comments notes, 2 of them are being investigated.
Unfortunately though, police forces around the world are not tasked with solving and prosecuting cases like this, which involve at least, extreme malfeasance, and more likely, malice with the goal of protecting oneself within X public/private institute they have a position in. This is a massively high profile case, so it will get some attention.
Instead the task is for the police is increasingly to mediate minor interpersonal disputes between individuals (easy wins) and ignore anything bigger and more complicated.