investigation movies or documentaries : two different views

watching a documentary on how the French police works to investigate a criminal case, I was struck by how reality diverges from fiction. in fiction the police officer works for the sake of truth, in reality the agent looks like he is working for the sake of his career , to get promoted by nailing the suspect with all possible means and receive a better pay check and more comfortable position later on. a bit like in a bank or any other institution working with such incentives. there you go, welcome to the world! the line between truth and manipulation is thin , up to the lawyers to defend the accused.