matt4077 writes "For eight years, several hundred police officers across multiple European countries have been chasing a phantom woman whose DNA had been found in almost 20 crimes (including two murders) across central Europe. It now turns out that contaminated cotton swabs might be responsible for this highly unusual investigation. After being puzzled by the apparent randomness of the crimes, investigators noticed that all cotton swabs had been sourced from the same company. They also noted that the DNA was never found in crimes in Bavaria, a German state located at the center of the crimes' locations. It turns out that Bavaria buys its swabs from a different supplier."