Sarah Cafferkey made a fatal mistake when she befriended Steven Hunter and kept in touch over Facebook.
Eight days after she vanished from her home at Bacchus Marsh, on Melbourne's northwestern fringe, the body of the 22-year-old woman was found in a house which Hunter shared with another man at Point Cook, in the city's southwest.
Police yesterday arrested 47-year-old Hunter, a convicted killer, in connection with Cafferkey's murder.
They said he was in custody and helping with their inquiries.
Hunter had suggested he and Cafferkey catch up during a conversation via Facebook just five days before she was reported missing.
He posted, "Love the pics ... Looking good, heartbreaker," and "Catch up when you got free time ... There better be a beverage handy," beneath a photo of Cafferkey on November 4.
Cafferkey left her home on November 9, visited a nearby friend the following day, then disappeared.
Her mother, Noelle Dickson, told Melbourne's Herald Sun that she had grown increasingly alarmed when Cafferkey did not return home, especially as she suffered from acute bronchial spasms and needed medications.
"She hasn't been home and that tells me something's wrong," she said before the tragic discovery at Point Cook.
Police found the body on Sunday morning when they searched the Point Cook house and collected evidence.
Now it has emerged that Stevens has a dark history.
In the early 1980s he was convicted of a number of crimes, including criminal damage, assault, and burglary.
In 1986 he was working at a supermarket with 18-year-old Jacqueline Mathews and persuaded her to drive him to a remote area near Tullamarine, where he made unwanted sexual advances, police alleged.
He stabbed Mathews to death and went back to work. Later he returned and burnt the car, with the body inside.
Hunter claimed that it was Mathews who made the advances and that during an ensuing struggle he had accidently stabbed her with a pocket knife.
The trial judge described that claim as absurd and that burning the car and body was "cowardly and heinous", the Age reported.
The judge, sentencing Hunter to a minimum 13 years in jail, also said he had shown no remorse for the crime.
Two years into his sentence Hunter escaped from Pentridge Prison by scrambling over a wall with another prisoner.
His freedom was short-lived: he was caught within half an hour after he was seen in a nearby house washing the blood from cuts inflicted during his escape.
The Age said it was believed that Hunter served only 12 years of his sentence and that he had subsequently been convicted of other crimes, including kidnapping and sex offences.
-Additional reporting AAP