Cory Gregory, born in 1987, was a teenager residing in East Moline, Illinois. He initially attended Moline High School but later transferred to the Black Hawk College Outreach Center, an alternative education program, where he met Sarah Kolb. The two became close friends, sharing interests and social circles. At the time of the incident, Cory lived with his mother. Reports suggest that Cory developed strong feelings for Sarah, who identified as a lesbian and was not interested in a romantic relationship with him. Their friendship was intense, and they were often seen together, forming a close-knit bond.

On January 21, 2005, Sarah Kolb invited Adrianne Reynolds to join her, Cory Gregory, and another friend for lunch at a local Taco Bell. During the drive, Sarah confronted Adrianne about personal issues, leading to a heated argument. Upon arrival at the restaurant's parking lot, the confrontation escalated. Cory held Adrianne down while Sarah strangled her with a belt, resulting in Adrianne's death.

After the murder, Sarah and Cory transported Adrianne's body to Sarah's grandparents' farm in Aledo, Illinois. There, they attempted to burn the body using gasoline, but the effort was unsuccessful. They then enlisted the help of Nathan Gaudet, a 16-year-old acquaintance, who used a handsaw to dismember the body. The remains were placed in garbage bags and disposed of at the Black Hawk State Historic Site.

Adrianne's disappearance was reported when she failed to return home or show up for work. An investigation led authorities to Cory Gregory, who confessed to the crime and directed them to Adrianne's remains. Cory was arrested on January 31, 2005, and later pleaded guilty to first-degree murder and concealment of a homicide. On July 10, 2006, he was sentenced to 40 years for murder and 5 years for concealment, totaling a 45-year sentence.

In 2019, following an Illinois Supreme Court ruling that a 40-year sentence for a juvenile is considered a de facto life sentence and unconstitutional, Cory was granted a resentencing hearing. On March 9, 2022, the original 45-year sentence was upheld.