Complex sentence: His first recorded sex crime occurred in 1978 in his hometown of Tacoma, Washington, when he was 15 years old; in that incident, he raped a nine-year-old boy at gunpoint.
Split into simpler sentences: His first recorded sex crime occurred in 1978 in his hometown of Tacoma, Washington, when he was 15 years old. In that incident, he raped a nine-year-old boy at gunpoint.