Final answer:
Jeffrey Dahmer committed his first murder at the age of 18 in 1978.
Step-by-step explanation:
Jeffrey Dahmer committed his first murder at the age of 18. This occurred in the summer of 1978, shortly after his high school graduation. Dahmer's first act of murder was a part of a series of heinous crimes he would commit over the span of more than a decade. It's worth noting that understanding the history of such criminal cases contributes to social studies, particularly in the context of criminal psychology and the justice system. Dahmer is infamous for being a convicted serial killer and sex offender in the United States.