Nancy Marie O’Sullivan was 15 when she vanished from South Holland, Illinois, on the evening of Thursday, March 7, 1974. A freshman at Homewood‑Flossmoor High School who lived in nearby Homewood with her parents and ten siblings, she had returned to her family’s former neighborhood to visit friends and was last seen in the 1300 block of East 168th Place. A friend said she walked to the end of his driveway and accepted a ride in a blue Cadillac; she did not return home the next day and was reported missing by her father.

Nancy had run away briefly before but always returned; this time she left her purse and makeup behind, which family called uncharacteristic. The case was long handled as a runaway matter before investigators later reclassified her as endangered missing and came to believe she was the victim of foul play. Several people Nancy had been visiting are now deceased, and police say there is little definitive evidence about her last hours. The Homewood Police Department keeps the investigation open and has issued public appeals for anyone with information.

If anyone knew Nancy, saw a blue Cadillac in that neighborhood on March 7, 1974, or has information that might help, please share what is known with investigators.