"Dubbed the "phantom of Heilbronn", the woman was described by police as [Germany]'s most dangerous woman"
Investigators had connected her to six murders and an unsolved death based on DNA traces found at the scene.
Police now acknowledge swabs used to collect DNA samples were contaminated by an innocent woman working in a factory in Bavaria.
Police suspected the unnamed woman of being a serial killer who over 16 years carried out a string of six murders, including strangling a pensioner.
She was alternatively called the "woman without a face" and the "phantom of Heilbronn" after the city in southern Germany where she allegedly killed a policewoman.