Asa Robert, 18, slipped past the woman and into her Sheepshead bay home as she swept the street out front about 1:40 a.m., NYPD officials said.
Robert, who is 5-foot-9 and 160 pounds, lay in wait and attacked her when she came back inside, police said.
He demanded money at knifepoint, but she said she didn't have any, so he ransacked the place, police said.
At about 4 a.m., he raped the woman before snatching an umbrella and a bag of clothing and fleeing, police said.
The victim was taken to Kings County Hospital for evaluation, police said.
Police said she has been instrumental in helping identify Robert, who they characterized as "vicious."
He hadn't been arrested as of Wednesday morning, police said.
He was arrested in 2014 on robbery charges in Crown Heights, police said.