Ronald Gene Simmons Sr. was born on July 15, 1940, in Chicago, Illinois, to Loretta and William Simmons. His early life faced a significant change when his father passed away from a stroke on January 31, 1943. Within a year, Loretta married again. This time, she wed William D. Griffen, who worked as a civil engineer for the U.S. Army Corps of Engineers. In 1946, the family moved to Little Rock, Arkansas, due to Griffen's job. This move was the first of several relocations across central Arkansas over the following years.

As a young man, Simmons faced challenges in his education. He dropped out of school on September 15, 1957, and chose to join the U.S. Navy. His first assignment was at Naval Station Bremerton in Washington. There, he met Bersabe Rebecca "Becky" Ulibarri. They married in New Mexico on July 9, 1960. Over nearly two decades, they had seven children together. In 1963, Simmons left the Navy, and about two years later, he joined the U.S. Air Force. During his time in the military, he had a successful career, earning accolades such as the Bronze Star Medal and the Vietnam Gallantry Cross. Simmons served for 20 years before retiring as a master sergeant on November 30, 1979.

After his military service, Simmons and his family experienced various issues that led to a significant change in their lives. On April 3, 1981, the Cloudcroft, New Mexico Department of Human Services began investigating him for allegations related to his daughter, Sheila. Fearing arrest, Simmons fled New Mexico with his family. They initially moved to Ward, Arkansas, and later settled near Dover, Arkansas, in the summer of 1983. The family lived on a 13-acre piece of land they called "Mockingbird Hill." Their home was built from two old mobile homes and lacked basic amenities such as a telephone and indoor plumbing.

In Dover, Simmons held multiple low-paying jobs. He worked as an accounts receivable clerk at Woodline Motor Freight but left due to inappropriate conduct. He later worked at a Sinclair Mini Mart for about 18 months before quitting in December 1987. By that time, the family living in the home had decreased to seven members, as two of the older children had moved out and started families of their own.

In late December 1987, Ronald Gene Simmons decided to kill his entire family. On December 22, he first killed his wife, Rebecca, and his eldest son, Gene, using a crowbar and a .22-caliber pistol. He then killed his three-year-old granddaughter, Barbara, by strangling her. All the bodies were hidden in a cesspit he had made the children dig.

After waiting for his other children to come home for Christmas break, Simmons told them he had gifts. He first killed his 17-year-old daughter, Loretta, by strangling and drowning her in a rain barrel. He continued killing his other children, Eddy, Marianne, and Becky, in the same manner, and also placed their bodies in the cesspit.

On December 26, Simmons invited more family members for the holidays. The first victims he killed were his son Billy and his daughter-in-law, Renata, both shot dead. He then drowned their 20-month-old son, Trae, and shot his oldest daughter, Sheila, along with her husband, Dennis. He also strangled Sheila's seven-year-old daughter, Sylvia, and his other grandson, Michael, who was just over a year old. After all the murders, he laid the bodies out in neat rows in the living room, covering them with coats and other items.

On December 28, Simmons went on another shooting spree. He drove to Walmart and bought another gun. His first target was a law office where a secretary named Kathy Kendrick worked. Simmons shot and killed Kendrick, then moved to an oil company office, where he shot the owner, Russell "Rusty" Taylor, wounding him. He killed James David Chaffin, who was an employee at that location, and then shot at another employee but missed.

He kept going to Sinclair Mini Mart and shot two more people there. His last stop was the Woodline Motor Freight Company, where he shot his former supervisor, wounding her. Finally, he ordered an employee to call the police. When they arrived, he surrendered without resistance.

Simmons was arrested and later convicted for the murders. He faced trials for the shootings of Kendrick and Chaffin first, then for the murders of his family. He received the death penalty in both cases. He refused to appeal his death sentence and was executed by lethal injection on June 25, 1990.