Half a million dollars is on offer for anyone who can provide information about a laneway sexual assault in the CBD last year.
The young woman, who has asked to be known as Amy, was dragged off Flinders Street and attacked in the early hours of Saturday, June 9, last year.
Police have now offered the huge reward in exchange for information leading to the conviction of the man responsible.
It's alleged he came out of a hostel and followed the then 18-year-old down Swanston Street, putting his arm around her and attempting to kiss her before dragging her into the alleyway and locking the high metal gates.
She had been out with friends and was walking to catch a tram when she was grabbed.
"It had a very big effect on my life," Amy said, speaking publicly about the attack for the first time.
"At first, I was just fully in denial but it ended up making things more difficult for myself.
"I wasn't able to focus at uni and eventually had to leave altogether."
She said she was now more easily scared, less trusting and always on edge.
Detectives have re-released images of a man they believe is in his 20s and of African appearance, that they want to talk to about the crime.
They also want to speak to two men who helped the distraught woman after the assault.
"This is a horrendous crime that occurred at what is probably the busiest intersection in Melbourne," Detective Inspector Steve Wilson said in a statement on Tuesday.
"We know that there were plenty of people around at that time, so I'd urge anyone who remembers seeing anything on that night to come forward."