Hamilton police are looking for the public's help in identifying a suspect involved in a violent sexual assault where a woman was dragged into a downtown alley last weekend.

Police have released a composite drawing of a man they say is involved in the daytime attack, which happened on Catharine Street North, near Rebecca Street, on Sunday.

The suspect is described as a white man in his 40s or older. Police said he is approximately six-feet-tall with a thin build and a large beard. He was wearing a waist-length green jacket, tan pants and black work boots.

Police believe the suspect said something to the victim shortly before the attack, but she did not respond.

The victim — a woman in her 60s — did not know the man and went into a nearby building to visit someone.

After a "short period of time," she re-emerged from the building and was quickly dragged into a nearby alley and attacked around 2 p.m., police said.

Detectives aren't sure if he was waiting for the woman, but hope to be able to clarify that from surveillance video that detectives are sorting through.

Police do not believe it is tied to any other sexual assault cases.

The woman was injured and required treatment in hospital. She has since been released.

Anyone with information is asked to call Det. John Tselepakis at 905-540-5545 or Crime Stoppers at 1-800-222-8477 (TIPS).