Police post images of a man they want to talk to while investigating sexual assault in Melbourne

Victoria Police has released a man's CCTV images (pictured) that they seek to identify after a sexual assault in the Melbourne CBD

Victoria Police has released a man's CCTV images (pictured) that they seek to identify after a sexual assault in the Melbourne CBD

Victoria Police has released a man's CCTV images (pictured) that they seek to identify after a sexual assault in the Melbourne CBD

Police have intensified their pursuit of a predator that dragged a teenage woman into an alley in Melbourne and sexually assaulted her, more than three months after the savage attack.

Now they have released CCTV images of a fourth man that the officers seek to identify after the assault in the CBD of the city on June 9.

The woman was attacked while walking down Flinders Street to Swanston Street shortly after 1.45 am, leaving her "extremely traumatized."

The man captured in the CCTV images, released on Wednesday, may have spoken to the victim at the time of the incident, "police said in a statement.

He is described as African in appearance and wore a swollen black jacket with red lining, light blue jeans and white runners at that time.

Detectives hope that the man can provide information to help them in their investigation and also want to talk to anyone who knows him.

Police launched a public appeal last month to find three men who helped the victim after the incident.

One has already shown up but the police are still looking for the others and now they have re-posted CCTV images of the two 'good Samaritans'.

The man in the CCTV images (pictured) is described as being of African appearance wearing a swollen black jacket with red lining, light blue jeans and white runners at the time

The man in the CCTV images (pictured) is described as being of African appearance wearing a swollen black jacket with red lining, light blue jeans and white runners at the time

He wore a swollen black jacket with red lining, light blue jeans and white runners at the time

He wore a swollen black jacket with red lining, light blue jeans and white runners at the time

The man in the CCTV images (pictured) is described as African-looking and wore a swollen black jacket with red lining, light blue jeans and white runners at the time

While the woman walked, a man approached the girl, put his arm around her shoulders and neck and began talking to her as she walked, police said.

He pulled the woman towards him and kissed her as they passed through the Metro tunnel.

She pushed him and continued walking but the man grabbed her again.

He then dragged the woman into an alley behind metal doors, locked the doors and sexually assaulted her, police said.

The woman screamed before fleeing to Flinders Street.

Police have also re-posted CCTV images of two "good Samaritans" men who helped the victim after the incident.

Police have also re-posted CCTV images of two "good Samaritans" men who helped the victim after the incident.

Anyone who acknowledges witnesses is encouraged to contact the police

Anyone who acknowledges witnesses is encouraged to contact the police

Police have also re-posted CCTV images of two "good Samaritans" men (pictured) who helped the victim after the incident, but have yet to report

Three men walking nearby noticed the anguished woman and helped her get in touch with a friend and arrange a trip home. She did not tell the men that she had been assaulted, police said.

The man who assaulted the woman is described as a man in his 20s, about 178 cm tall, with a thin complexion, dark brown skin and short hair.

He wore a dark-colored jacket and long pants.

Anyone with information that communicates with Crime Stoppers is requested to 1800 333 000.

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