Shawcross was born in Kittery, Maine, the first of four children of Arthur Roy Shawcross and Elizabeth “Bessie” (“Betty”) Yerakes Shawcross. His family moved to Watertown in New York State when he was young. While several later tests showed Shawcross’ intelligence to be sub-normal or even “borderline retarded”, he received As and Bs in his first two years of grade school but was later tested to have an I.Q. of 86, signifying below average intelligence.
Shawcross said throughout his childhood, he was a frequent bed-wetter. He later claimed his mother would insert foreign objects into his rectum and that his aunt performed oral sex on him when he was 9, and that during junior high school he had sexual relations with his sister. Shawcross had a reputation at school as a bully and would frequently act out violently. He dropped out of high school in 1960.
In April 1967 he was drafted by the Army at age 21. At this time, Shawcross divorced his first wife and gave up the rights to their 18-month-old son, whom he never saw again. He served one tour of duty in Vietnam, where he boasted of grotesque combat exploits, such as “beheading mama-sans and nailing their heads to trees as a warning to the Vietcong” — though in fact he never saw combat.
After Vietnam he was stationed at Fort Sill in Lawton, Oklahoma as an armorer. His second wife Linda experienced several aspects of his disturbing behavior, especially his penchant for starting fires; an Army psychiatrist told her that Shawcross derived “sexual enjoyment” from fire starting.
