Simon Kitson‘s engrossing The Hunt for Nazi Spies: Fighting Espionage in Vichy France makes the case that Vichy France — and in particular, 1940-42 Vichy, before Operation Torch triggered the outright German occupation of Vichy France — had an active counterespionage program working against German spies.
Once recruitment in the German secret services was suspected, evidence was needed to carry out an arrest. The general rule was to delay arresting suspects so as to be able to tail them to find out who their contacts were and the exact nature of their activities. This is what happened with Alfredo Castoldi, an Italian working for the Germans. Castoldi made the acquaintance of someone named Perez in a bar and tried to convince him to provide military information. Perez pretended to accept but the next day he went to tell all to the local police chief. The police did not arrest Castoldi right away but asked Perez to maintain contact with him and to earn his trust and find out the nature of his intentions and his network. The evidence acquired in this way was so convincing that on 3 November 1941, at 7:30 in the morning, Castoldi was executed by a French army firing squad in Algiers.
Castoldi was not an outlier. Several dozen German spies may have been shot by Vichy France in the 1940-42 period. Kitson notes that it is
difficult to ascertain the exact number of German spies sentenced by Vichy military courts who were actually executed by the firing squads of the French army. [Paul] Paillole claims there were forty-two of them. In research for the present study, I found formal proof of eight such executions, but Paillole’s figure seems credible for two reasons. Firstly, during the postwar trial of Marshal Philippe Petain, Ernest Lagarde, the former director of political affairs in the Foreign Affairs Ministry, claimed there were about thirty such executions in 1941, which does not exclude a total of forty-two for the years 1940-42. Secondly, there is a register of Petain’s decisions concerning appeals for clemency from individuals condemned to death for activities ranging from Communism to army mutinies to espionage. In espionage cases, the registry does not specify for which country a particular spy was working, but it would seem that, after cross-checking the names listed with other sources used for the present study, there were twenty-seven confirmed cases of Axis spies having their appeal for clemency refused. A further twenty-three cases in which clemency was refused also appear to involve Axis spies. Of course, in a handful of instances where the appeal for clemency was rejected, executions may still not have been carried out as a result of the invasion of the southern zone by the Germans, which brought a sudden end to official executions. This registry nevertheless adds credibility to Paillole’s estimate.