Irma Dugard was a French half-elf working as a housekeeper for Corvus Lestrange. After the birth of his son, Corvus the father, sent the half-elf with his two children, Corvus and Leta, to New York in 1901, to be adopted by Mary Lou Barebone. On the voyage over, frustrated with Corvus’ constant screaming, Leta exchanged her half-brother with another baby (Credence Barebone). Shortly afterwards the ship on which they were sailing floundered and sank during a storm and Corvus drowned. Irma took care of the young Credence, signing his adoption papers.
In 1927, she was visited by Credence and Nagini, in a small attic space at 18 Rue Philippe Lorand, Paris. He wanted to learn the truth about his family. After a short meeting, she struck with a killing curse by Gunnar Grimmson on Gellert Grindelwald’s instructions. (CG)
Dugard is possibly derived from the French "du garde" or "of the guard".