Amy* was walking towards a tram stop on Flinders Street after a night out with friends when she felt an arm around her shoulder.

The man, who emerged from the doorway of United Backpackers, began to ask her questions: what was her name, where she was from. She felt uncomfortable and gave short responses in the hope he would lose interest and leave her alone.

But he suddenly tightened his grip, put her in a headlock and dragged her into a secluded laneway, locked her behind high metal gates, and raped her.

Amy, now 19 years old, has spoken for the first time about the horrendous assault on June 9 last year, as police announce a $500,000 reward for information that leads detectives to her attacker.