Beloit police are investigating a strong-arm home-invasion. Captain Vince Sciame says a little after 7:00 last night, a man knocked on the door of a home in the 700 block of Lincoln Avenue on the city's west side. Sciame says the residents, a couple in their 80's, believed him to be a door-to-door salesman. Once inside he attacked the man, who suffered minor injuries. The suspect robbed the couple of a wallet and jewelry. The suspect fled on foot. Most disturbing to police was the suspect's disregard for the security and well being of such an elderly couple. The suspect is described as a black male in his late 20's to early 30's, wearing a dirty white t-shirt and blue jeans.