Kimberly Diane Cargill was born on November 30, 1966, in Jones County, Mississippi. She grew up facing significant challenges in her early life. At the age of 11, Cargill was sexually molested by a family member. This traumatic experience was noted in a psychiatric report later in her life.

As an adult, Cargill was married three times and had four sons. Her first marriage ended in divorce in December 1995. She married her second husband in June 1996, but that marriage also ended in the early 2000s. Cargill's third marriage began in 2005 and ended in divorce as well.

Kimberly's relationships with her family were troubled. Her children and ex-husbands described her as often abusive toward them. One of her ex-husbands reported a severe incident where he witnessed Cargill physically assault her young son from a previous marriage. This incident contributed to their decision to separate. On another occasion, Cargill had a conflict with her third husband over snacks, which escalated into a physical altercation. She was then accused of setting a fire in his apartment out of anger.

Additionally, Cargill showed abusive behavior toward her own mother. She reportedly choked her mother when she was upset. She also exhibited similar aggression toward two of her sons, including locking them in their rooms for hours as a form of punishment. 

On June 18, 2010, Kimberly Cargill murdered Cherry Walker in Whitehouse, Texas. Cargill was concerned that Walker would testify against her in a custody hearing about her children. To prevent this, Cargill met with Walker under the pretense of taking her out to dinner. During this meeting, Cargill killed Walker, causing her death by asphyxiation.

After the murder, Cargill placed Walker's body on the side of a rural road, eight to ten miles away from where Walker lived. She attempted to destroy evidence by dousing Walker's clothes in lighter fluid and setting them on fire, burning Walker's body before leaving the scene. The next day, Walker's body was discovered, but it took several days to identify her.

Investigators quickly identified Cargill as the prime suspect in the murder. She was arrested and initially charged with causing injury to a child. Later, she faced a charge of capital murder, which can lead to the death penalty in Texas. In October 2010, she was formally indicted for capital murder. The trial began on May 8, 2012. Cargill pleaded not guilty, claiming that Walker had a seizure and died unexpectedly while they were driving.

The prosecution presented forensic evidence suggesting that Walker's death was not accidental. Experts testified about the details of the autopsy, concluding that she died from asphyxiation and that this indicated homicide. On May 18, 2012, the jury found Cargill guilty of capital murder. During the sentencing phase, witnesses described Cargill's history of abuse towards her children and former spouses.

On May 31, 2012, the jury recommended the death penalty. Cargill was sentenced to death by lethal injection on June 7, 2012. She filed several appeals against her conviction and sentence, but each was rejected by the courts. As of 2025, Cargill remains on death row at the Patrick O'Daniel Unit in Texas, waiting for an execution date that has not yet been scheduled.