He's been described as dark-skinned, possibly Maori or Polynesian, in his early 20s with short hair and very distinctive tattoos.
His left arm was fully tattooed from the shoulder to the wrist in a Maori or tribal design.
His right arm was also tattooed from the shoulder to the elbow in what was believed to be a Maori or tribal design.
Police have been door-to-door canvassing the Victory area, as well as conducting a scene examination.
The scene where the attack took place was visible from a popular public walkway and Mr Langridge said it was likely that people would have been using the path as the attack took place.
Police would like to hear from anyone who was on or near the Railway Reserve about 2.30pm yesterday, and they plan to maintain a significant presence in the area until the offender is caught.
"This man is a risk to himself and the wider community and I strongly encourage him to hand himself in,'' Mr Langridge said.