The perpetrators could have escaped punishment if they had taken extreme measures at the time of committing the crimes, but with the development of human science, it has become possible for crimes to be discovered even if decades have passed.
Crimes that remained unknown until DNA analysis revealed them. How does DNA reveal the genetic fingerprints of humans? And what is the possibility of a match between two people?
The science of forensic entomology began centuries ago, but it has now evolved to the point where it is possible to know the time and place of the crime, and perhaps the weapon used as well.