Delbo supplied lodging for underground (resistance) fighters in 1943 after she got them to trust her. She then informed on them and they were arrested by the Gestapo.[6] For instance, she informed on Svend Otto Nielsen (codename John) and Jens Lillelund (Finsen) of the Holger Danske resistance group for which she received 20,000 Danish kroner. The Gestapo came for Nielsen after he left Delbo's apartment. Nielsen was wounded, arrested, and tortured. Jens Lillelund, code name of Finn, tried to kill her for being an informer. He failed and fled to Sweden. Delbo escaped to Norway, but later returned to Copenhagen and operated a dressmaking shop under an assumed name, Mrs. Dam.
Ella von Cappeln, a former nun who worked for the resistance movement, had won Delbo's trust and gained access to her apartment, and then helped two comrades gain entry.[8]
In March 1944, it was reported in the Dagens Nyheter, that Delbo and Pelving had been arrested and wounded.[9] Delbo was then shot dead, also in the month of March 1944,[6][10] in her apartment on Sankelmarksgade at Vesterbro, Copenhagen by two men.[9] They were resistance fighters from the Holger Danske resistance group.
Delbo also owned an apartment on Saxogade.[9] Max was arrested in May 1945 for his work for the Gestapo.[3]
