A spokesman for Konstanz Police, Markus Sauter, said in a statement that after releasing the images of the suspect last week more than 650 people contacted police on a special hotline, but officials said no concrete lead to the suspect had emerged at that stage.
Authorities believe the baby food was tainted by the same person who threatened last week to poison food in supermarkets and drug stores in Germany and overseas if his demands for money weren't met, according to German news reports.
Officials in the city of Konstanz say that the threatening email was sent to unspecified food retailers.
The authorities urged the public to remain calm and to check that the products they buy have not been manipulated or opened before making purchases. He said he could not give further examples, however, because he didn't have the suspect's record.More news: Ikea Enters 'Gig Economy' by Acquiring TaskRabbit
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If convicted, the man could face between five and 15 years in prison for extortion under threat of force. He did not rule tacking on charges of attempted murder, as well.
He threatened to poison 20 jars of baby food if stores didn't pay the $11.8 million - equal to 10 million euros - by Saturday.
Employees of a drugstore in Peine, about 500 kilometers (320 miles) north of Friedrichshafen in the state of Lower Saxony, said they saw a man similar to the presumed suspect.
As many as five jars of baby food were found contaminated with ethylene glycol, one of the most common ingredients of anti-freeze. The substance can cause kidney failure, brain damage and death. A man was seen on camera placing the products on the shelf. He left the store before they could stop him.