What details in The Death of Marat show Charlotte Corday’s assassination of Marat?

In Jacques-Louis David’s painting The Death of Marat, the assassin Charlotte Corday is not depicted in the scene. Instead, David uses specific symbolic details to represent her act of violence and the circumstances of the assassination:1

• The Murder Weapon: A bloodied knife lies on the ground near the bathtub, signifying the instrument used to stab Marat.1
• The Evidence of Admittance: Marat’s left hand still clutches the letter Corday used as a pretext to gain entry to his room, where she claimed to be seeking his protection.1
• The Fatal Wound: A visible, bleeding gash is depicted just below Marat’s collarbone, marking the location where he was stabbed.1

By omitting the assassin, David focuses the viewer's attention entirely on the victim, elevating Marat to a martyr for the Revolutionary cause by drawing visual parallels between his death and the stigmata of Christ.1