An elderly man fell and broke his hip moments after having his wallet stolen from him in Kettering on Sunday (July 12).
The incident happened at about 6.30pm in an alleyway off Havelock Street.
The victim, who was on crutches, was followed into the alleyway by the offender who stole his wallet.
The elderly man fell and broke his hip as a result of the shock caused by the incident.
The offender is described as a white man in his early twenties with dark curly hair and a slim build, about 5ft 8in, clean-shaven and wearing a blue jacket and jeans.
Officers investigating the incident are keen to speak to a man they think may have witnessed the incident, and had walked past the offender just before it happened.
The witness is a white man with a medium build, receding hair, wearing a light-blue T-shirt and jeans and carrying a green bag.
Anyone with information should phone police on 101.
Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111 or use the anonymous online form at www.crimestoppers-uk.org.