TIL that after hunting a serial killer whose DNA was found at 40 crime scenes across Germany and Austria for 16 years, police discovered the DNA belonged to a woman working at the swab factory

Not necessarily, medical sterilization is to primarily prevent infections and the bar for this is "Free from viable microorganisms"

The bar for laboratory use is much much higher where even trace amounts of anything, no matter how dead or "unviable", can throw things wildly off