She then took the severed body part to a police station in Chicago. A man with a matching injury turned up soon after at a hospital in the city.
Police are planning to interview the 21-year-old man who allegedly tried to rape the woman near Chicago Police Headquarters.
He allegedly accosted the 42-year-old woman and ordered her to perform a sex act on him. The woman then bit off part of his genitals, said Chicago Police Department spokesman Thomas Donegan.
The man has undergone surgery at Michael Reese Hospital and Medical Centre, according to hospital spokeswoman Sandra Wilks. Doctors were unable to reattach the body part and the man is now sterile, reports the Chicago Tribune.
Wentworth Area detectives are waiting for the man to recover sufficiently from surgery to talk to him. No charges have been filed.