Someone has been posting used condoms to women living in Melbourne.
The letters, containing handwritten messages and used condoms, have been mailed to residential addresses across the south-eastern and eastern suburbs.
More than 65 female victims have come forward so far, Victoria Police said on Wednesday, and many had received multiple letters.
The first incident was reported to police on March 20, with the most recent occurring on Monday.
"It is believed that most of those who reported the material have received multiple letters, all with the suspected used item included," police said in a statement.
"Officers believe the victims are linked and are part of a targeted attack."
Other media are reporting that all the targeted women reportedly graduated from Kilbreda College, in the suburb of Mentone, in 1999.
The investigation continues and Victoria Police were due to hold a press conference later on Wednesday.
