Bernadette was an Executioner at MACUSA in 1920s New York.
When Tina Goldstein and Newt Scamander were accused by Auror Percival Graves of using an Obscurus to cause destruction, Bernadette led Tina to the Death Cell. She extracted happy memories from Tina’s mind and dropped them into the pool of potion to lure her to her death. When Goldstein begged for mercy, Bernadette said “It don’t hurt” (WFT).
With the help of his Bowtruckle, Pickette, Newt unshackled himself and hit Bernadette with a spell that knocked her down, causing her wand to fall into the vat of potion and be swallowed by black bubbles. Tina was rescued by Newt’s Swooping Evil creature (WFT).
Other canon notes and references
Also known as "Executioner 1" in the Fantastic Beasts script (WFT).