Nailah Franklin's uncle, Jon Merrill, and family friend Andrew Holmes told WFLD-TV that authorities have confirmed the body is Franklin's.
Neither Chicago nor Calumet City police would immediately confirm the identification.
Franklin's family gathered Thursday near where Calumet City Police Chief Russell Larson said officers discovered a woman's unclothed body. Bond said the body was discovered about 4:46 a.m.
Franklin's car had been found Friday night near an abandoned building in nearby Hammond, Ind.
She recently had filed a police report about threatening phone calls she received from a man she dated briefly. Chicago police on Monday said they had interviewed someone Franklin dated, but have not named a suspect in her disappearance.
The pharmaceutical sales representative for Indianapolis-based Eli Lilly was reported missing Sept. 19 after she didn't show up for a work meeting. Since then, family members and volunteers have papered the city with fliers and taken out a newspaper ad seeking the public's help.
The family also offered a $10,000 reward for information leading to her whereabouts.