I am absolutely sure they invented more serial killers than existed in the world and multiplied them to 100, maybe. What is interesting – our famous serial killer Andriy Chekatilo is mentioned from time to time or Jack the Ripper and so on. I understand that they are trying to make their characters more vivid with this applying to real history, still they are very scarce in it.
Though if we look to this page https://en.wikipedia.org/wiki/List_of_serial_killers_by_number_of_victims we will find so many of them but they are not so popular (or I am not of interest).
The first one is to show that serial killers are made by their environment, their life story, other's attitude and behavior to them. It seems like partly the guilt is taken from them to the society so that we all can be not only the victims but those who can fix the problem.
The other one is to show people how they should behave if they found themselves in such a situation with killers. What can help ordinary people to survive or have more time to be found and rescued.
While watching I surely find in my head thoughts whether I would be found if became a serial killer. And in fact I can not imagine myself in such a situation since I do not find the need to do that, to have a souvenir from a victim and so on. So as far as I can see people do not become killers usually just because they do not want and not because of laws and prisons.
But it was very interesting to find out that any person has a comfort zone. Places were we feel ourselves safe – work, home, spare time. From this three points we can easily create a triangle on the map and with very high possibility we will find a victim, commit a crime and leave the body in that area.
Victimology usually shows us what kind of persons will be chosen as victims. And they are always connected with real life – those the killers want to have revenge over. Those they miss much. Those played an important role in stress situation.
And a profile shows us what kind of person commited a crime. For example, I was very surprised to know that rapes almost never happened with people of different races. As if we are attractive to each other only if we are of same race, unconsciously. And women use poisons, men use weapon. Like that.
In fact, I am already get bored with watching so many victims, but I am such a person that can not leave it and not watch until the end.