There is absolutely no possibility of Angela Young becoming a police officer, let alone her being promoted to Detective Sergeant.
Not only does she show herself to be completely incapable of rational thought, a DS's job is to "supervise and monitor the handling of information, intelligence and evidence and record keeping ensuring alignment with legislation, policies and guidance", in ignoring all evidence that didn't fit her strange theory and even attempting to make an arrest before receiving all the evidence reports, Ms Young failed on all points.
Also, the woman who made up a theory of the crime which ignored all the evidence, while appearing to have some kind of seizure, would not have passed a psychological assessment.