Shannan Gilbert

Shannan Gilbert was a 24-year-old sex worker from New Jersey who disappeared in Oak Beach, Long Island in May 2010 after calling 911 in distress from a client's home, sparking the discovery of the Gilgo Beach serial killings. Police initially focused on her disappearance separately from the other victims, whose remains were found along Ocean Parkway during the search for Gilbert. Gilbert's own skeletal remains were found in a marsh near Oak Beach in December 2011; her death was officially ruled undetermined, fueling debate about whether she was a victim of the same serial killer. Her disappearance transformed what might have been a cold case into one of New York's most extensive serial murder investigations.

Sources: Wikipedia: Gilgo Beach serial killings