The incident occurred at about 7:15 p.m. in the area of Greyrock Place and Forest Street, police said. The man walking his dog was confronted by a black male wearing a hoody who said he had a knife and demanded the man's wallet, police said.
The man answered he didn't have a wallet with him, but the suspect didn't buy that response, police said.
"The suspect then insisted and told him not to mess around," Sgt. William Brevard said.
The victim then offered up $500 in cash that he had on him as well as his house and car keys - something the robber hadn't requested, police said.
The suspect then fled the scene. The victim was not hurt. Police had no information on the type of dog the man was walking.
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