After some initial uncertainty over whether they had apprehended the correct person, German authorities on Saturday said they believed they had the supermarket extortionist in custody.

The 55-year-old man was detained near Tübingen, south of Stuttgart on Friday evening after members of the public tipped off investigators. Authorities had released a surveillance camera image of the man believed to be behind the threats.

Still, police said consumers should take care and check the safety seals on the products they buy and report any suspected tampering to the authorities.

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The subject of the manhunt sent an email to police earlier this month threatening to distribute poisoned foodstuffs into German supermarkets if he wasn't paid a sum believed to be more than €10 million ($12 million).

In mid-September authorities discovered five jars of baby food laced with ethylene glycol, an odorless, colorless, sweet-tasting compound used in antifreeze. It can cause kidney failure, brain damage and death in humans.

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Caught on camera

The poisoned jars were found in a supermarket in Friedrichshafen in southern Germany. A man was seen on camera placing the products on the shelf.

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. He left the store before they could stop him.

The extortionist had threatened to poison foodstuffs all over the country.

More than 650 people contacted authorities on a special hotline, police said on Friday.

"As of this morning, we received 650 calls, with many more coming afterward, but so far no concrete lead to the blackmailer has emerged," said Markus Sauter, a spokesman for the police headquarters in the nearby city of Konstanz. About 12 officers were manning the lines around the clock.

Investigators told customers to look for any interference in packaging when purchasing products.

aw/sms (dpa, AFP)