The owner of a briefcase which was snatched in Corby Old Village was attacked by the thief.
The incident happened outside Chester House in Chapel Lane on Tuesday, September 16, at about 10.30am.
A police spokesman said: “The victim gave chase and was then assaulted. The offender ran off into Post Office Close flats and may have headed towards the High Street.”
The offender is white, about 6ft, with a slim to medium build. He was wearing a blue hooded top, dark-coloured tracksuit bottoms and trainers. He was also wearing a distinctive skull motif face-covering.
Witnesses, or anyone with information, are asked to call Northamptonshire Police on 101. Alternatively, they can call Crimestoppers on 0800 555111.