Police are appealing for witnesses after a knife-wielding robber threatened staff at two shops and made off with cash from one of them.
The offender walked into the Premier Express store in Mansfield Road, Alfreton, shortly after 7am on Saturday.
He threatened a member of staff with a knife and made off with a small amount of cash, running off along Prospect Street.
Detectives believe the same man went into the Stop and Shop store in Market Street, South Normanton, at about 5.45pm that day.
The offender again threatened a member of staff with a knife and demanded cash but was challenged and fled empty-handed.
Nobody was injured in either of the offences.
Police want to hear from witnesses or anyone who might have information on the person responsible.
The offender was white, in his late teens or early 20s, about 5ft 8in and of medium build.
He wore black skinny jeans, light grey shoes and a light grey hoodie with the hood up.
He also had a black scarf concealing the lower half of his face.
Witnesses or anyone with information which could help the investigation should call Derbyshire police on 101 or Crimestoppers on 0800 555 111.