On 22 September 1977 Folkerts and Elisabeth von Dyck set out to return a car to a Dutch car rental business in Utrecht. The car had been rented by Sigrid Sternebeck and used in connection with the kidnapping and murder of Hanns Martin Schleyer. The surroundings were under surveillance and the police tried to arrest Folkerts. Folkerts fatally shot Dutch policeman Arie Kranenburg (born 10 June 1931) and seriously wounded a second officer. Folkerts was arrested, Elisabeth von Dyck, originally mistaken for Brigitte Mohnhaupt, managed to escape.