Sebastián with British diplomat Michael Creswell, ("Monday"), who gave her money for the Comet Line's expenses plus messages to take back to France. While returning to Paris she reinforced the system of safe houses and helpers along the route and paid necessary expenses, although most members of Comet Line never received any compensation for their expenses. Estimates of the number of times that de Jongh successfully escorted downed airmen across the border into Spain in 1941 and 1942 vary from 16 to 24 round trips. The number of persons, mostly airmen, she escorted successfully is about 118. Captured Comet Line members and their families took great risks. The escape lines became more dangerous after November 1942, when southern France was occupied by the Germans and the whole of France came under direct Nazi rule. During the war members of the Comet Line were betrayed and hundreds were arrested by the Geheime Feldpolizei and the Abwehr and were executed or deported to German prisons and concentration camps. In January 1943, de Jongh led three British airmen south by train from Paris to Saint-Jean-de-Luz. From the railway station they walked in rain for two hours to the village of Urrugne, in the French Basque country – the last stop on the escape line before the walk over the Pyrenees. With the airmen and de Jongh was her favorite Basque guide Florentino Goikoetxea, a smuggler wanted by the police on both sides of the border. They arrived at the safe house belonging to Frantxia Usandizanga, a Basque woman, intending to continue to the border, distant. However, the river Bidasoa on the border was in flood and it would be too dangerous to attempt to cross. Goikoetxea went to another house to spend the night and de Jongh and the three airmen spent the night at Usandizanga's house. They next morning, 15 January 1943, de Jongh, the three airmen, and Usandizanga were arrested in the house by ten German soldiers. They had been betrayed, probably by a farm worker named Donato whom de Jongh knew but did not trust. De Jongh was sent first to Fresnes prison in Paris and eventually to Ravensbrück concentration camp and Mauthausen. She was interrogated 19 times by the Abwehr and twice by the Gestapo. Although she admitted being the leader of the Comet Line to protect her father who was under suspicion, the Germans did not believe that