A 33-year-old woman was groped by a stranger as she walked along Weedon Road in Northampton.
The incident happened at about 6.40am on Thursday, 15 October. The victim was approached by a man who groped her before running away when she screamed.
The offender is described as white, aged 25-30, about 5ft 7in tall and wearing a cream coat and a cream hat. He was carrying a red rucksack.
Witnesses or anyone with information is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.