A 41-year-old man was robbed in the street in Lincoln on Sunday, February 26.
The man was walking along Monks Road at about 12.30am when he was approached from behind, pushed to the ground and threatened with a knife.
The victim was then dragged into Bernard Street where his pockets were searched by a man while he was restrained by a woman.
The man was described as white, in his early twenties and was around 6ft tall. He was of medium build and had short dark hair and a local accent. He was wearing light coloured clothing.
The woman was white and in her late teens to early twenties, around 5ft 3in tall and was of slim to medium build, with short dark hair and a fringe that had blonde tips. She was wearing dark clothes and trainers.
Any witnesses or anyone with any information on the offenders is asked to call Lincolshire Police as soon as possible via the non-emergency 101 number, or via independent charity Crimestoppers anonymously on 0800 555 111.