The man stole money, jewelry and a television, Amormino said.
The woman's son and grandson were in the home at the time, he said.
The woman had gone to the garage to get a towel for her son and grandson, who were taking a shower and did not hear the confrontation.
She was confronted in a hallway after re-entering the home, Amormino said.
The suspect may be the same man who has carried out five other similar robberies in surrounding cities in the past two months or so, Amormino said.
He is black, about 6 feet and 200 pounds, and in his 20s, Amormino said.
The Sheriff's Department plans to release a composite sketch to help track down the bandit.
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