Rhonda Belle Thomley was born around 1907 in Alabama to James Robert Thomley and Mary Frances Grimes. Details about her early life are scarce, but she eventually settled in Montgomery, Alabama, where she worked as a waitress. Over the years, Martin entered into multiple marriages, each marked by tragic outcomes. She had seven children, five of whom died under mysterious circumstances before reaching the age of 12. Her personal life was characterized by instability and a series of familial losses that would later draw significant scrutiny. ​

Between 1937 and 1951, a series of deaths occurred within Martin's immediate family. Her daughter, Emogene Garrett, died on July 9, 1937, followed by her second husband, George W. Garrett, on December 24, 1939. Subsequent deaths included her daughters Anna Carolyn Garrett on May 15, 1940, and Ellyn Elizabeth Garrett on August 1, 1943. Her mother, Mary Frances Gibbon, passed away on February 11, 1944. The pattern culminated with the death of her fourth husband, Claude Carroll Martin, on April 27, 1951. Initially, these deaths did not arouse suspicion, as they were attributed to natural causes. ​

The turning point came when her fifth husband, Ronald Martin—who was also her former stepson—fell gravely ill but survived, albeit with paralysis. Medical examinations revealed arsenic poisoning, prompting authorities to exhume the bodies of Martin's previous family members. Autopsies confirmed the presence of arsenic in multiple victims, leading to Martin's arrest in March 1956. Initially, she confessed to poisoning her mother, two husbands, and three of her children but later recanted her admissions regarding two of the children's deaths.

Between 1937 and 1951, a series of deaths occurred within Martin's immediate family. Her daughter, Emogene Garrett, died on July 9, 1937, followed by her second husband, George W. Garrett, on December 24, 1939. Subsequent deaths included her daughters Anna Carolyn Garrett on May 15, 1940, and Ellyn Elizabeth Garrett on August 1, 1943. Her mother, Mary Frances Gibbon, passed away on February 11, 1944. The pattern culminated with the death of her fourth husband, Claude Carroll Martin, on April 27, 1951. Initially, these deaths did not arouse suspicion, as they were attributed to natural causes. ​

The turning point came when her fifth husband, Ronald Martin—who was also her former stepson—fell gravely ill but survived, albeit with paralysis. Medical examinations revealed arsenic poisoning, prompting authorities to exhume the bodies of Martin's previous family members. Autopsies confirmed the presence of arsenic in multiple victims, leading to Martin's arrest in March 1956. Initially, she confessed to poisoning her mother, two husbands, and three of her children but later recanted her admissions regarding two of the children's deaths.

In 1956, Martin was tried and convicted for the murder of Claude Carroll Martin. Despite her confessions to multiple murders, she was only prosecuted for this single count. She was sentenced to death and, after a series of appeals and a clemency hearing, was executed in Alabama's electric chair on October 11, 1957. Her execution marked her as the third woman to be electrocuted in Alabama and the last until 2002. ​