Gayno Gilbert Smith was born on January 23, 1938, in Keokuk County, Iowa.

On May 27, 1962, Gayno Gilbert Smith murdered six members of the McBeth family in Iowa. He killed Andrew McBeth, 51, and Dora McBeth, 41, along with their three children: Amos, Anna, and Donna Jean, who were aged 19 and 17. Smith, who was 24 at the time, was living with the McBeths and was also their nephew. Smith confessed to this crime and to the murder of his stepmother, Juanita Smith, who had been missing since 1961.

On the night of the murders, Donna Jean and her siblings had gone to a dance. During their absence, Smith remained behind. When the children returned home with their parents after the dance, they found the lights in the house turned off. Using flashlights, they searched the house and discovered their parents' bodies in the garage. When they tried to call for help, they found that the phone lines had been cut.

Smith confronted them with a flashlight and a gun. He shot Amos and Donna Jean, injuring Patsy Lou, the youngest sibling, as well. Though wounded, Patsy managed to escape to another room. She found her sister Anna dead. Smith chased Patsy outside, and she fled through the ditches until she reached a nearby farmhouse to get help.

After the murders, Smith went into hiding. He was discovered four days later in a barn near Lake Wapello and arrested. Following his confession to both the McBeth murders and the earlier murder of his stepmother, Smith faced possible execution. Prosecutors sought the death penalty, but he pleaded guilty to the charges instead.

During the trial, Smith’s defense chose not to dispute his sanity, and he was ultimately sentenced to six life terms in prison without the chance of parole. His sentences were to be served consecutively. The youngest victim, Perry, who was just an infant at the time of the murders, was adopted by his uncle and raised alongside his uncle's own children.

In 1971, Smith sought a new trial, but his attempt failed. While in prison, he focused on education and worked towards earning a college degree, showing an interest in rehabilitating juvenile delinquents. He expressed thoughts on improving the prison system as well.

Gayno Smith died on May 16, 2005, due to heart problems. He was cremated and buried next to his mother. After his death, Perry shared his feelings about Smith, stating that he wished Smith had been sentenced to death instead, expressing relief at his passing.