Donald Edward DeMag was born on December 15, 1922, in Burlington, Vermont. He was the eldest of five children and had a troubled youth, accumulating various misdemeanors, including motor vehicle offenses and grand larceny. At 17, he was sent to a reformatory school. Despite his early troubles, he married young and had children. DeMag suffered from health issues, including deafness in one ear and seizures, possibly due to scarlet fever in childhood.

In 1948, at age 25, DeMag, struggling financially, sought a loan from 81-year-old Francis Racicot, a local harness shop owner. Upon refusal, DeMag fatally bludgeoned Racicot with an iron shaker, stealing less than $100. He was apprehended five days later and sentenced to life imprisonment.

While serving his sentence at Vermont State Prison, DeMag escaped in 1950 but was recaptured after 15 days. In 1952, he and fellow inmate Francis Blair escaped again by crashing a laundry truck through the prison gates. During their escape, they attacked Elizabeth Weatherup and her husband in Springfield, Vermont, beating them with a lead pipe during a robbery attempt. Elizabeth died from her injuries. The duo was recaptured two days later.

DeMag was tried, convicted of first-degree murder, and sentenced to death. He was executed by electrocution on December 8, 1954, at Vermont State Prison in Windsor, becoming the last person executed by the state. He was buried at Holy Family Cemetery in Essex Junction, Vermont.