People in the Singen area north east of Lake Constance fear the man may strike again, while police cannot tell them not to worry, a spokesman admitted.
“The uncertainty among local people is of course considerable,” he said. “And at the moment we simply cannot give them the all-clear.”
The man kidnapped a 44-year-old taxi driver in Singen on Tuesday, seriously wounding and then raping her, police confirmed.
A day later he stabbed a 23-year-old woman taxi driver to death in Hagnau, not far away.
He is thought to be between 20 and 25-years-old, and speaks broken German.
This weekend police investigations were concentrated around the rural countryside of Baden-Württemberg, where many farms employ foreign workers to harvest fruit and vegetables. They have gathered more than 500 clues, but do not yet have a firm lead.
The local Stuttgarter Zeitung reported on Saturday that many taxi drivers in the region were angry at only having been warned by police quite a long time after the first attack.