Associated Press reports that German authorities said Saturday they are confident that a 53-year-old man arrested a day earlier is behind a blackmail attempt that saw jars of poisoned baby food placed on store shelves in southern Germany.

Prosecutors said investigators found the same poison — ethylene glycol, a compound used in antifreeze — when they arrested the man Friday near the southwestern city of Tuebingen.

Chief prosecutor Alexander Boger told a news conference in Konstanz, on Germany’s southern border, that the man hadn’t confessed but the evidence against him was substantial.

DNA found on the baby food jars and pictures taken with a supermarket surveillance camera also pointed to the suspect, who wasn’t identified due to German privacy rules, prosecutors said.

Authorities and companies received an email this month threatening to poison unspecified food at German retailers inside the country and beyond unless more than 10 million euros ($11.8 million) was paid by Saturday.

The blackmailer alerted authorities that five jars of baby food at shops in Friedrichshafen, near Konstanz, had been tampered with. Officials located the jars and found they contained ethylene glycol but said there’s no evidence that anyone was poisoned.