Why are the most infamous serial killers turning out to very likely have been cops, and/or their murders covered up by cops and even entire law enforcement departments and "justice" systems?

https://www.youtube.com/watch?v=ar5tbEf8u_s

https://www.amazon.com/Jack-Ripper-Policeman-New-Suspect/dp/1399017527

https://www.youtube.com/watch?v=g0-EpMcraX4

https://www.youtube.com/watch?v=u4YIotUciNY

https://www.youtube.com/shorts/y-9sR6B86mg

https://www.amazon.com/Black-Dahlia-Red-Rose-Corruption/dp/1631492268

https://www.youtube.com/watch?v=Ti2rs5vvz3Q&t=1016s

https://www.youtube.com/watch?v=wHlvMWOoKZg