In 1989, Dahmer resided at his grandmother's residence in West Allis, Wisconsin, and an incident known as the "Box Incident" unfolded. By that point, Dahmer had already unalived five young men. During a visit from his father, an intriguing one-foot square metal and wood box caught his dad's attention. Piqued by curiosity, he inquired about its contents, but no one had any knowledge of what lay inside.

Dahmer's father, recalling the moment, expressed, "I asked Jeff to open it up. I simply wanted to see what was concealed within." However, an argument ensued as Dahmer refused to comply. Frustrated, his father threatened to take the box to the basement and open it with a screwdriver. This threat visibly agitated Dahmer, who couldn't have possibly imagined the grim contents of the box. Eventually, an agreement was reached to open it the next day and then dispose of it.

Remarkably, the box was never opened, and it remained a chilling mystery. It later came to light that this unopened box contained the mummified head and genitals of a young man Dahmer had encountered in a Milwaukee gay bar.