On the 18th of June, 1602, he brought the marshal before the court of Parliament.

The inquiry lasted three weeks.

Biron was unanimously condemned to death by a hundred and twenty-seven judges "for conspiracies against the king's person, attempts upon his kingdom, and treasons and treaties with the enemies of the kingdom." The king gave to this sentence all the alleviations compatible with public interests.

He allowed Biron to make his will, remitted the confiscation of his property, and ordered that the execution should take place at the Bastille, in the presence of certain functionaries, and not on the Place de Greve and before the mob.

When Biron found himself convicted and sentenced, he burst into a fury, loaded his judges with insults, and roared out that "if he were driven to despair and frenzy, he would strangle half of those present and force the other half to kill him." The executioner was obliged to strike him unawares.