The innocent-looking boy in this photo would one day become one of the most infamous killers in modern history. Born in May 1960 in Milwaukee, Wisconsin, Jeffrey Lionel Dahmer came into the world as a cheerful and energetic child. His parents, a young chemistry student and a teletype instructor, had high hopes for their firstborn. But just before his fourth birthday, something shifted. After undergoing double hernia surgery, Dahmer’s personality drastically changed — the once lively boy became quiet, withdrawn, and detached.

At school, teachers described him as timid and isolated. With a father often away studying and a mother struggling with depression, Dahmer showed early signs of emotional abandonment. Soon, disturbing behaviors emerged. He began collecting and dissecting dead animals, burying them around the yard and displaying skulls on makeshift crosses.

By his teens, Dahmer’s troubling impulses grew. At 15, he mutilated a dog in a gruesome incident. He also began drinking heavily, calling alcohol “my medicine.” His parents’ bitter divorce left him alone in the family home at 18. Just three weeks after graduating high school in 1978, Dahmer committed his first murder after picking up a hitchhiker. It would be the beginning of a 13-year killing spree.

In total, he murdered 17 young men, dismembering many and engaging in cannibalism and necrophilia in horrifying attempts to create compliant “companions.” Dahmer was finally arrested in 1991 after a victim escaped and alerted police. He was killed in prison in 1994 at age 34 — a chilling end to a life that began with innocence but descended into unimaginable darkness.