Reta Phyllis Mays was born on June 16, 1975, in Reynoldsville, West Virginia. She grew up in a small town and likely experienced a typical childhood for that area. In November 2000, Mays joined the United States Army and became a member of the West Virginia National Guard. She served in the military until April 2001, and then again from February 2003 to May 2004. During this time, she was deployed to Iraq and Kuwait with the 1092nd Engineer Battalion.

After her time in the military, Mays worked as a corrections officer at the West Virginia Department of Corrections. She was employed at the North Central Regional Jail in Greenwood, West Virginia, from 2005 until 2012. While working there, she was involved in a lawsuit filed by an inmate who claimed he had been beaten by Mays and other officers. The lawsuit was dismissed.

In 2015, Mays began working as a nursing assistant at the Louis A. Johnson Veterans Medical Center in Clarksburg, West Virginia. It is noted that she did not have the certification or license required for this position. Additionally, nursing assistants at the facility were not authorized to administer medications, including insulin.

Mays was also a longtime member of a local church called Monroe Chapel United Methodist, located about twenty minutes from Clarksburg in Lost Creek.

In June 2015, Reta Mays started working as a nursing assistant at the Louis A. Johnson Veterans Medical Center in Clarksburg, West Virginia. At the hospital, she did not have a certification or license to care for patients. In July 2017, she was assigned to work overnight shifts in Ward 3A. During this time, several elderly patients began to show sudden drops in their blood sugar levels.

Over the next eleven months, the hospital reported that multiple patients died from hypoglycemia. Some of these patients were not even insulin-dependent. In a short span, four deaths occurred within sixteen days. One victim was Archie Edgell, an 84-year-old Korean War veteran. He experienced a dangerous drop in blood sugar levels but was stabilized, only to suffer another drop later and pass away. An autopsy revealed that he had been injected with insulin multiple times.

The hospital initiated an internal investigation into the unexpected deaths. In June 2018, Mays was fired, and the investigation was handed over to the Inspector General for the United States Department of Veterans Affairs and the Federal Bureau of Investigation. During the investigation that followed, Mays was interviewed three times but denied any wrongdoing. Investigators built a circumstantial case against her, noting her peculiar internet searches about female serial killers.

In July 2020, Mays was arrested and charged with the murders of eight individuals. The charges were later updated to seven counts of second-degree murder and one count of intent to commit murder linked to the death of another patient, Russell R. Posey Sr. He died two weeks after being injected with insulin. Mays eventually pled guilty to the charges in July 2020 and admitted in court that she had murdered the patients.

On May 11, 2021, Mays received a sentence of seven consecutive life sentences and an additional 20 years for attempted murder. During her sentencing, she expressed remorse for her actions, stating she could not offer comfort to the victims' families. Mays was ordered to pay restitution to the families of the victims and other related parties.

Following her plea, Mays was moved to a low-security prison facility in Alabama. She is currently ineligible for parole.