Also location, there are vast vast areas in some countries like USA, Australia, Russia etc that aren't inhabited or monitored in any way and if someone buries a body in eg the outback or in a huge American lake or something chances are police etc aren't even going to know to look there! Let alone where to start in an area of like 50000 acres of ranch land!
Then there's if they dump the body at sea, huge areas of oceans completely unexplored.
Or (even more gruesome) they do things like chop the body into little bits and scatter or cremate it or acid baths etc...
Serial killers are constantly evolving just like the rest of us.
Contrary to many fictional tv shows and films they don't always target the same type of victims or use the same methods to kill or get their victims or dump the bodies in the same place repeatedly. Some do this stuff, many don't.
@LucyLime At one point a minimum of 3 kills = serial killer that's no longer the case and police/law enforcement will define based on things other than number of kills
"angels of mercy" and "last min hero" type serial killers in the medical profession I suspect are more prevalent than anyone would like to admit. And I speak as an ex hcp. It's still such a position of trust that they're rarely suspected, add in pressure/busyness due to lack of resources/manpower and the knowledge they have it's almost a perfect storm.
@Whirlwind14 That doesn't surprise me at all. I KNOW I've met a few (convicted now released, mainly dv)
The fetishising of serial killers is quite bizarre! Even when ted Bundy had escaped and killed very young girls in the most violent and tortuous ways he had loads of young women fans until he was executed.
@Porcupineintherough I don't think a financial motive rules one out. Shipmans main motive was financial, some of the most famous and historic serial killers had money as motive eh h h Holmes one of the earlier American serial killers.
Ditto revenge, Jack the Ripper one theory (and I think there was evidence to support this possibility) was that he was vengeful due to having caught an sti by using sex workers - and remember these were fatal at this time, pre penicillin!
Plus, do the computer systems of all the state police talk to each other?
No I have family in USA one of whom is ex law enforcement but still knows how it works and is still in contact with ex colleagues, often even the different counties within a state don't communicate properly. There's a lot of issues with territory marking, trying to keep a capture within your specific police force (there's different types of police too - city forces, sheriffs dept, Feds, stats police etc) some of whom are elected rather than otherwise earn the post so have very political agendas for how they act - mainly wanting to keep their own depts stats looking good, so there's problems with reports not being recorded etc also old outdated equipment, officers not knowing how to correctly use the systems etc
We have the same issues here in Uk. 2 police forces I believe have now been pulled up, reprimanded and put on "special measures" for things like not recording all reported crime, failing to investigate, dismissing victims as unworthy of attention etc
Law enforcement throughout the world needs much improvement.