The Assassination of the Duke of Guise (1563)
On the eve of entering Orléans, Duke François de Guise was killed by Poltrot de Méré. When questioned, the latter denounced Théodore de Bèze, Admiral de Coligny and Jean de Parthenay. The admiral responded to these accusations but Jean de Parthenay, who was locked up in Lyon, could not add his name to the protest of 12 March 1563, signed by Châtillon, La Rochefoucauld, and De Bèze.
The presumptions against Jean de Parthenay are that during the siege of Lyon he spoke of killing de Guise. Moreover, during the siege, Jean de Parthenay sent Poltrot to Admiral de Coligny and their accusers saw in this evidence of a plot.
Antoinette d'Aubeterre hired François Viète, a jurist, as a legal adviser, who addressed suspicions of complicity by Jean V de Parthenay. In Lyon, Jean V and his lawyer researched documents about his actions. Viète also produced a summarization of Jean de Parthenay's behavior the previous year, during his administration of the city of Lyon.