According to the 11th and 12th century writers Bishop Otbert of Liège (Passio Frederici) and William of Malmesbury, the killers were hired by Empress Judith, because of Frederick's regular criticism of her dissolute way of life.
Utrecht | Utrecht (city) | Frederick the Great | Frederick | Frederick II | Frederick II, Holy Roman Emperor | Frederick Russell Burnham | Frederick Roberts, 1st Earl Roberts | Frederick Law Olmsted | Frederick I, Holy Roman Emperor | Frederick Forsyth | Frederick Douglass | Frederick, Maryland | Utrecht University | Prince Frederick, Duke of York and Albany | Frederick III | Frederick I | Frederick Delius | Frederick William III of Prussia | John Frederick II, Duke of Saxony | Frederick III, German Emperor | Frederick William IV of Prussia | Frederick Schomberg, 1st Duke of Schomberg | Frederick I, Margrave of Brandenburg-Ansbach | Frederick III, Holy Roman Emperor | Treaty of Utrecht | Frederick, Prince of Wales | Frederick Funston | Frederick Ashton | John Frederick II |