Not just uncaught murderers, there are a lot of people who have killed without legally being considered murderers.
People who killed people in accidents such as driving accidents or hunting accidents
People who killed in self defense
Soldiers who killed enemy soldiers
Executioners
Police officers who have killed on duty
Doctors and nurses who have made mistakes that accidentally killed patients
Used to work with the criminally insane. I’ve also met a LOT of pedophiles. Not many because they actually were crazy but because they were trying to get declared as such to not get fucked up in prison. Most of them aren’t even actually attracted to children they just wanna victimize someone and children are smaller / weaker and less able to advocate for themselves. The one thing pretty much all of them have in common is a pitiful combination of sadism and cowardice.