Theresa Hall was a 9-year-old girl from Decatur, Illinois, who was killed on Halloween night, October 31, 1984. She had been trick-or-treating with her 12-year-old cousin Sherry Gordon and her 7-year-old sister Patricia; the three were reported missing that night. Two days later, on November 2, Theresa and Sherry were found strangled in a vacant apartment in the Longview Housing Project near their home. Patricia was found alive in a closet in the same apartment, cold but unharmed.

Investigators determined the two girls had been strangled—one with a piece of clothing and the other with an electrical cord. Early leads included a report of an older man driving a rusty four-door Oldsmobile, but that lead was later dismissed. In 2009 DNA testing matched evidence from the scene to Melvin Johnson, a Decatur resident with a prior 1978 conviction for taking indecent liberties with a child. Johnson had died of stomach cancer in Texas in 2003, so he was never tried for these murders.

The identification of Johnson closed a painful gap for the families after 24 years; authorities also examined links between Johnson and other killings from the 1980s.