A Berlin university on Thursday withdrew her doctorate from a prominent former German minister following a long saga over plagiarism allegations that led to her resignation last month.

Franziska Giffey resigned as German Minister for Women and Families in mid-May, but the center-left Social Democrat is still one of the main candidates for mayor of Berlin in the September elections.

The Free University of Berlin said it concluded that Giffey’s doctorate was obtained with “deception of the independence of his academic results.” He said his thesis used texts and references from other authors without labeling them sufficiently as such.

Doctorates are in high demand in Germany and have already caused problems for senior politicians.

In 2011, then Defense Minister Karl-Theodor zu Guttenberg lost his doctorate and resigned when it emerged that much of his thesis was not his original work. Two years later, then Education Minister Annette Schavan resigned after a university withdrew her doctorate.

Allegations of plagiarism led the University of Berlin to revise Giffey’s 2010 thesis on the policy of the European Union’s executive body, the European Commission. Giffey said in 2019 that she would step down from the government if her doctorate. has been revoked. The university initially decided to issue a reprimand, but not to revoke his title.

In November, the university said it would reconsider the decision after an expert report raised questions about whether it was only empowered to issue a reprimand. Giffey then said she would stop using the academic title of “doctor”.

Announcing her resignation last month, she insisted that she had written the thesis “to the best of my ability” and added: “I regret it if I made mistakes on this.” Giffey added that if the university decided to revoke her academic title, they would accept it.