Authorities and companies received an email this month threatening to poison unspecified food at branches of German retailers inside the country and beyond unless more than 10 million euros (US $11.8 million) was paid by Saturday.
Police say they've cracked the case of the supermarket extortionist who threatened to poison Germany's baby food supply if his demands were not met.
Police said they had found some baby food spiked with ethylene glycol, a colorless, odorless liquid used in the manufacture of antifreeze, which can be deadly if consumed.
While police believe they do have the suspect in custody, there was reportedly no confirmation that it was the man pictured in the surveillance images.
There were no reports of any injuries.
The colourless substance has a sweet taste and is known to attract children and animals.
Authorities are "of the firm opinion" that the nabbed alleged racketeer is the only culprit and no others were involved, said chief prosecutor Alexander Boger said at a news conference Saturday, said the Sueddeutsche Zeitung newspaper. "[But] there is no reason for panic or hysteria".
Officials said they believe all of the contaminated food has been found but warned shoppers to remain alert to any possible signs of product manipulation.
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. The footage was made public to help in the search.