Sachs was educated in an English-style boarding-school, lived for a year in London and worked in a bookshop, and returned to Paris..

In 1925 he converted to Catholicism and decided to become a priest, though this didn't last upon meeting a young man on the beach at Juan-les-Pins.

After involvement in a number of dubious business activities, he traveled to New York, where he passed himself off as an art dealer. Returning to Paris, he associated himself with leading homosexual writers of the time - Cocteau, Gide and Max Jacob - with all of whom he had stormy relationships whose precise nature is unclear. At various times he worked for Jean Cocteau and Coco Chanel, in both cases stealing from them.

Sachs was mobilized at the start of World War II, but was discharged for sexual misconduct. During the early years of the Occupation, he made money out of helping Jewish families escape to the Unoccupied Zone. He may also have been an informer for the Gestapo. He was later imprisoned in Fuhlsbüttel.

One story of Sachs' death is that he was lynched by other prisoners and his body was thrown to the dogs.