The discovery was made by police patrolling Princes Park at around 3:50am.
Fire crews worked to remove the offensive material, reportedly 25 metres in size, which appeared to be deliberately painted next to the floral memorial at the park.
The vandalism comes just days after 22-year-old Eurydice Dixon's body was found in the middle of a soccer pitch in Carlton North.
A 19-year old man was charged with one count each of murder and rape.
Police said the markings will be removed as soon as possible. The investigation is ongoing.
Anyone with further information is urged to contact Crime Stoppers on 1800 333 000.
This article originally appeared on New Idea.