Vancouver police have released a composite sketch of a suspect in a sex assault that occurred last week in the city's downtown core.

Investigators say a 19-year-old woman was walking alone ar around 10 p.m. on July 28 when a stranger approached.

The man tore at her clothes and groped her before fleeing the scene. The woman, who did not know her way around the city, wandered alone for hours alone until a Good Samaritan offered her a sweater.

She called police several hours later after being urged by a friend.

The suspect is described as a 5-11 tall man, 25 to 35-year-old with dark skin, a muscular build, and dark brush-cut hair.

He had a well-kept goatee with a thin line of facial hair along his jaw line, a distinct wrinkle at the bridge of his nose and a scar under his left eye. He was wearing a black tank top and blue jeans.

Anyone with information on the assault is asked to contact the Vancouver Police Department's Sex Crimes Unit at 604-717-3117 or Crime Stoppers at 1-800-222-8477.

Investigators would also like to speak to the Good Samaritan.