Authorities said the factory worker's DNA was found at 39 crime scenes. Police pursued the trail for two years before realizing that the DNA collected at the crime scenes came from the cotton ball maker.
Bild reported Thursday that police had linked the killer to seven homicides, including a 2007 slaying in which a 22-year-old policewoman in Heilbronn was shot dead and her colleague was seriously injured.
Bernd Meiners, a spokesman for the public prosecutor's office in Saarbrucken, acknowledged the mistake Wednesday.
"There are considerable doubts about the existence of the 'phantom killer'. The DNA has instead been linked to investigation materials," he was quoted as saying.