Laquiante, an officer of the Strasbourg criminal court, designed a beheading machine and employed Tobias Schmidt, a German engineer and harpsichord maker, to construct a prototype. Antoine Louis is also credited with the design of the prototype. France's official executioner, Charles-Henri Sanson, claimed in his memoirs that King Louis XVI (an amateur locksmith) recommended that the device employ an oblique blade rather than a crescent one, lest the blade not be able to cut through all necks; the neck of the king, who would eventually die by guillotine years later, was offered up discreetly as an example. The first execution by guillotine was performed on highwayman Nicolas Jacques Pelletier on 25 April 1792 in front of what is now the city hall of Paris (Place de l'Hôtel de Ville). All citizens condemned to die were from then on executed there, until the scaffold was moved on 21 August to the Place du Carrousel.