Police have released a CCTV image of the man who held up a Hemel Hempstead shop with a carrier bag covering his face in an attempt to capture him.
The robbery, in which the culprit branded a knife and asked a staff member to empty the till, occurred at the Day One store in Bennetts Gate at around 8.40am on Friday.
The man entered the store with a white Londis carrier bag over his head and walked behind the counter before taking cash and fleeing towards Leys Road.
The staff member was not injured during the incident.
Det Con Paula Mowbray from Hemel Hempstead’s local crime unit, investigating, said: “It is quite unusual for a robbery to be committed where the suspect uses a carrier bag as a means to attempt to conceal their identity.
“We would like to speak with the man pictured as he may be able to assist our enquiries. I would also like to hear from anyone who may recognise him.”
A 19-year-old man from Hemel Hempstead has been arrested in connection with this incident and is on police bail, but it is believed he is not the man pictured.
Call police on the police non-emergency number 101 quoting crime reference number D1/14/2764, or Crimestoppers anonymously on 0800 555 111, with information.