A 69-year-old woman in Kiyosu, Aichi Prefecture, was arrested Tuesday for allegedly placing on store shelves margarine whose use-by dates had expired three years ago.

Tsuyako Kishi reportedly put four margarine packages on the shelf of a supermarket in Kiyosu on May 23. The best-before date on the boxes was July 28, 2013, according to the Aichi Prefectural Police. They said the woman has admitted to the charges and they are investigating the motive.

The police have also found packages of flour bearing use-by dates between 2007 and 2008 in the supermarket and two other stores in Nagoya, and are investigating whether Kishi was involved in placing the food there.

Two boxes of margarine and a bag of flour with expired use-by dates had been purchased by customers at the supermarket in Kiyosu. All of the products were returned before being opened, and no damages were reported.

The police identified Kishi from security camera footage and reports from supermarket staff, and found 12 margarine and flour packages with old best-before dates at her home.