Tattoo key to solving sex attack

A unique tattoo could be to key to solving a sex attack south of Adelaide.

A man with a solid black chest tattoo, which has four points coming off an arch, sexually assaulted a woman at Goolwa South in January, police said after releasing an artist's sketch of the tattoo on Thursday.

The suspect was described as "extremely unkempt" with a "distinctive" bad body odour.