How can the Angiolini Report change the seedy side of Police Culture it exposed?

[Anyotherdude]

The report, published today, outlines the incompetence of various Police Forces in checking the background of applicants for working with the Police, in the light of the myriad opportunities available to spot that Wayne Cozens should never have been employed as a police officer, due to his predilection to violent sex attacks against women.
As Angiolini points out, there are probably more people like this employed at this point. How can they be routed?
Surely they are obvious? It’s well-known that due to Cozen’s general demeanour he was nicknamed “the rapist”.
How can these people be identified, if their colleagues don’t seem to be able to report them for traits that strongly suggest they are potential offenders?