According to Biography, Jeffrey Dahmer had an unhappy childhood, one where he was profoundly affected by his parents’ crumbling marriage. A highly introverted young man, he had very few friends and already had a serious drinking problem as a teenager. He would later claim that he was just 14 years old when he first started entertaining thoughts of necrophilia and murder.

Four years later, Dahmer would commit his first murder — at that time, he had just turned 18 years old and had only recently graduated from high school. On June 18, 1978 (via The New York Times), he met another fresh high school graduate named Steven Hicks, a fellow Ohio native who was hitchhiking to a rock concert. Instead of driving him to the concert, Dahmer invited Hicks to hang out with him at his parents’ house, where the two young men had several beers. When Hicks, who was already drunk at that point, attempted to leave, Dahmer struck the 18-year-old in the head and strangled him with a barbell until he died. He then dismembered Hicks’ corpse and placed his body parts in plastic bags; initially, he buried the remains behind his parents’ home, but he would later exhume them, crush the bones with a sledgehammer, and scatter them in the nearby woods.

After murdering Hicks, Dahmer spent the next three years in the Army before getting discharged. He would run afoul of the law multiple times in the years that immediately followed, though it was only in 1987 when he killed his second victim, kicking off a crime spree that lasted until his 1991 arrest.