Thousands of people gathered in Australia on Monday night to pay tribute to comedian Eurydice Dixon, whose rape and murder in an inner-city park triggered an emotive plea by prime minister Malcolm Turnbull to “change the hearts of men”.

But just hours before a vigil in Melbourne for the 22-year-old, who was killed last week while walking home from a stand-up show, vandals painted lewd markings in the grass around a floral memorial for her in the park where she died.

"I would never have expected something so vile to happen in such a sacred place, at such an important time," Megan Bridger-Darling, who organised the vigil, told ABC News.

"I'm genuinely disgusted that this happens in our society and that we have created a culture where this is funny. It is absolutely galling."

Ms Dixon was raped and murdered last week shortly after telling her boyfriend in a text: “I’m almost home safe. HBU? (how about you?)”. Her body was later found by a passer-by at Princes Park, about a half-mile from her home.