A teenager wanted for

allegedly raping an 82-year-old woman

was spotted in Brooklyn Thursday night, sources said.

Asa Roberts, 18, who is wanted for an attack on elderly woman who let him inside her home, was spotted on Madison Street in Bedford-Stuyvesant 9:30 p.m., where he fled inside a school under construction, according to law enforcement sources.

Officers canvassed the building but all they found was a bloody shoe that belonged to Robert, a source said.

The teen allegedly raped the woman after she offered to make him a meal at her home on Monday.

The victim is recovering in a local hospital.