Katharina Kepler was married to Heinrich Kepler and had one daughter and three sons; one of them was Johannes Kepler. In 1615, a witch trial was initiated by Lutherus Einhorn who in his reign as Vogt of Leonberg (1613 - 1629) accused 15 women of sorcery and executed 8 of them. He acted in accordance with the will of the government and the public, which had asked for an investigation of sorcery, and issued an arrest of Katharina Kepler in 1615. Ursula Reinbold had accused Katharina Kepler of giving her a potion after an argument which had made her sick. Johannes Kepler defended his mother himself, with the assistance of his university in Tübingen. One of his student friends, Christopher Besoldus, assisted her juridically.
Her son took her away to Linz in December 1616. When she returned to Leonberg in the summer of 1620, she was arrested and imprisoned for fourteen months. She was told how she would be tortured, as a means of frightening her, but she refused to confess anything.
In October 1621, Kepler was able to effect her release. Katharina Kepler died the following year.