- "I was sent to his house to kill him but the job was finished by the time I got there. With what Marat was publishing it was either him or us. I don't recognize that list of names as Girondin, but you could ask some of our leaders. I'll write you an address, go there and show the list."
- ―Brignac on the assassination of Jean-Paul Marat, 1793.[src]
When the Jacobin politician Jean-Paul Marat began publishing articles threatening the lives of Girondists, the party resolved to kill him, sending Brignac to do the deed. By the time he reached Marat's house however, the Jacobin had already been killed. As a suspect, Brignac was imprisoned at St. Germain.
When questioned on the murder by Arno Dorian, Brignac was shown a list written by Marat, supposedly listing Girondists. Not recognizing any of the names, he told Arno to speak to the Girondist leaders at 39 rue des Cordeliers about the list.