Lee Monroe Betterton was born on March 24, 1872, in Kings Prairie Township, Missouri. He was one of fifteen children born to Lee Land Betterton and Mary Catherine Betterton, whose maiden name was Whittingdon. There is not much information about his early childhood or his upbringing.

As he grew up, Betterton became an adult and married Laura Elizabeth McCoy. They had several children together and lived a normal life on a farm in Kings Prairie Township. During this time, Betterton had only a few minor legal issues, primarily related to non-payment of fines. However, in 1904, his marriage began to face difficulties, and he and Laura argued frequently.

In the midst of their troubled marriage, an incident occurred where Betterton physically harmed Laura. This led to a crisis that resulted in her hospitalization. Laura eventually died from her injuries, but for reasons that are not clear, Betterton was never charged in connection with her death. After this event, he hired a woman named Rose Hudson to be their housekeeper. Betterton and Hudson developed a relationship and lived together as common-law partners.

Despite their relationship, Betterton and Hudson also had their struggles, and she left him multiple times, but always returned. On December 28, 1906, after another argument, she left him once again but soon accompanied him to visit his children. On their way home, Betterton consumed alcohol, which led to another confrontation.

In 1904, Lee Monroe Betterton and his first wife, Laura Elizabeth McCoy, got into a violent argument. During this conflict, Betterton beat Laura until she lost consciousness. Neighbors rushed her to the hospital, but she died from her injuries. Despite this, Betterton was never charged for her death. Afterward, he hired a housekeeper named Rose Hudson, and they developed a close relationship that resembled a marriage. However, this relationship was also troubled. On December 28, 1906, after another argument, Betterton stabbed Hudson three times while intoxicated, leading to her collapse. He then poured whiskey on her face before being arrested by a nearby train crew. Betterton confessed to the murder and pleaded guilty at his trial, receiving a 99-year prison sentence.

Betterton was paroled on September 25, 1917. He returned to Monett and married Elzadah Lockwood on June 11, 1918. They seemed to live a happy life, despite a house fire in March 1919. However, they divorced shortly after, only to remarry on July 1, 1919. To celebrate, they visited relatives in Vinita, Oklahoma. On July 9, during another argument, Betterton shot Elzadah three times. He attempted to shoot his daughter-in-law but was stopped by his son, Ernest. Betterton tried to blame his son for the shooting but was arrested and threatened to kill himself and family members while in jail.

Betterton's trial for murder began on July 29, 1919. After nearly three months, he was found guilty and sentenced to death. His execution was first scheduled for January 23, 1920, but after a mental evaluation confirmed he was sane, his execution date was rescheduled for July 9, 1920. On the anniversary of his wife's murder, Betterton was executed in the electric chair at the Oklahoma State Penitentiary in McAlester. He maintained his innocence until the end, stating he was ready to meet God. His final words were, "Goodbye, and God bless you all."