Not content with the punishment she had already dealt Medusa (turning her into a hideous monster, with snakes for hair), Athena sent Perseus to kill her. After many years of searching, Perseus eventually tracked Medusa down. Perseus defeated her by using her reflection against her, which turned her to stone. He then chopped off her head and put it on his shield, which he later gave to Athena to gain favor.
Many years after his death, Medusa was resurrected by her sisters. Medusa was initially afraid that he was still alive, but her sisters assured her that he was long dead. Medusa was relieved that he could no longer harm her, but was still hurt and angry that this so-called hero had once hunted her down like a monster and murdered her.