A tartan-scarved robber snatched a bag of money off a woman in broad daylight outside a bank in Altnagelvin on Monday.
Police are appealing for information after the woman was robbed outside the Danske Bank.
The incident occurred at about noon on Monday.
A woman was entering the bank with a sum of money in a bag when a man grabbed it and ran off.
He is described as being about 5ft 8inches tall and of a slim build. He was wearing grey tracksuit bottoms, a black jacket and hat and a tartan scarf.
A number of men chased the man down Church Brae, but he made his escape through the gardens of houses.
Chief Inspector Ivor Morton said: “We would like to hear from anyone who saw the man running away, or noticed him in the Belt Road area beforehand. We believe he was in the area for a time before the woman arrived at the bank. She was not physically hurt in the incident.”