A 76-year-old Derbyshire man was robbed at knifepoint by an intruder who forced his way into the victim's home.
The robber pushed his way inside after knocking on the man's back door in Oakley Avenue, Chesterfield, on Thursday night.
He stole cash and escaped in the direction of Hawksley Avenue after jumping over a fence.
Police described the attacker as white, in his late teens or early-20s, about 6ft 2in (1.8m) tall with a slim build.
He was wearing dark trousers, a dark jacket with the hood up and a white scarf across his face.
Derbyshire Police said a police dog was able to track the suspect's escape route along a footpath onto Hawksley Avenue, towards the tennis club, before losing the scent.
Anyone with information about the robbery, which happened at about 2240 GMT, or who saw a person getting into a vehicle on Hawksley Avenue at that time, should contact the force.