A man was knocked unconscious and left with facial injuries after being hit from behind while walking on a Daventry estate.
The victim was walking along Lincoln Way on Stefen Hill between 9pm and 10pm on Saturday, August 20, when he was hit to the back by an unknown person.
Police say nothing is believed to have been taken during the incident.
Anyone with information can contact Northamptonshire police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.