Tammi Jean Campbell was last seen on June 12, 1999, in Grove City, Ohio, where she had dropped off her 12-year-old son at a friend's house. She was going to visit another friend that night and then work the next day at CVS Pharmacy. However, she never arrived at work and has never been heard from again.

Her ex-boyfriend Gary Lee Robinson was found at her apartment the day after she was last seen. Robinson had allegedly been abusive towards Tammi, and she had moved from Kentucky to Grove City in 1998 to get away from him. He was sentenced to four years in prison for domestic violence and felonious assault in a case involving his stepdaughter.

Robinson was indicted for Tammi's murder in May 2009 and convicted of murder and evidence tampering in April 2010 after a four-day trial.