Sex fiend snapped at Melb beach

A quick-thinking woman took a photograph of a man who allegedly exposed himself and indecently assaulted her at a Melbourne beach.

The woman, aged in her 40s, was walking her dog along the foreshore path at Sandringham on January 3 when she was approached by a man wearing a towel around his waist at about 7.30pm, police say.

He fled the scene after being disturbed by passers-by, but not before the woman took a photograph of him.