Let s say a crime scene opens up some murder detectives are hired to clean it up.
One detective finds another detective s (who is working on the scene) DNA.
What happens to the detective whose DNA was found? Is he kicked off the case? What else happens?
Foofa
Detectives don't moonlight as crime scene cleaners. But in the case where a cop's DNA was found on a scene he/she was investigating it would probably be chalked up to sloppy police work. So in some 'Dexter' world a cop could in theory be a serial killer and get away with it if he/she just managed to be called to each and every scene so the DNA left could be explained (assuming it wasn't inside the victim's body cavity or something).
STEVEN F
Homicide detectives INVESTIGATE. They DON'T clean up crime scenes.
Anonymous
Certainly, you need much more than 1 detective as one can't simply solve a case by themselves.