Born 22 October 1922 in Luingne (Mouscron), Belgium, Desoubrie was the illegitimate son of a Belgian doctor. Never having a proper home and abandoned by his mother at an early age, he became a drifter and later took up a trade as an electrician.
Desoubrie was described as a short, stocky man with piercing grey eyes set behind a pair of moderately thick-lensed spectacles. He was always smartly dressed, with his light brown hair always neatly combed. His smile revealed bright gold fillings in his front teeth and he spoke excellent English.
World War II
When World War II broke out, the Belgian teenager eagerly accepted the Nazi propaganda, readily adopting their doctrines.
He entered the Gestapo in 1941, and infiltrated first the Resistant group Vérité Française, where he had 100 Resistants arrested, and then the "Le Gualès" network (after Charles Le Gualès de la Villeneuve, one of its leaders) where he had 50 Resistants arrested. He infiltrated other groups, such as the escape network known as the Comet Line, that helped Allied airmen whose planes were lost to return to Britain over France and Spain. He used various aliases including; Pierre Boulain, Jean Masson, Jacques Leman, and Captain Jacques, as he liked to be known.
After the Liberation, he fled to Germany. Although Desoubrie used the alias Jean Masson, he is not to be confused, as F. Venner did, with the Jean Masson (1910–1965) who participated to the creation of the traditionalist Catholic Cité catholique group, along with Jean Ousset, in 1946. Desoubrie was arrested after being denounced by his ex-mistress, and executed as a collaborationist in December 1949 in the fort of Montrouge, in Arcueil (near Paris).
- Review of Patrice Miannay's Dictionnaires des agents doubles dans la Résistance (Dictionary of Double Agents in the Resistance (French)
- Pitchfork, Graham (2003, p. 59). Shot Down and on the Run. Published by Dundurn Press Ltd. OCLC 52565302. ISBN 1-55002-483-3.
- Burgess, Colin (1995). Destination Buchenwald. Published by Kangaroo Press, Kenthurst NSW. OCLC 35019954. ISBN 0-86417-733-X.
- F. Venner, Extrême France, Grasset, 2006 (extract (French)