Martha Beck was born Martha Jule Seabrook on May 6, 1920, in Milton, Florida. She struggled with weight issues from an early age, which was attributed to a glandular problem. This led her to mature physically before many of her peers. During her childhood, Martha claimed to have faced significant hardship and trauma, including being raped by her brother and beaten by her mother.

As a young teenager, she ran away from home with Truman Capote, a boy who was only ten years old at the time. They made it to her uncle's house before they were found and returned home after just a day. After completing her education, Martha wanted to become a nurse. However, her weight made it difficult for her to find a nursing job. She started working as an undertaker's assistant, where she prepared bodies for burial. Eventually, she moved to California to work in a United States Army hospital as a nurse.

While in California, Martha became pregnant. The father refused to marry her, which was a significant source of shame during that era. She returned to Florida as a single mother. After the birth of her daughter, she had another brief marriage to a bus driver named Alfred Beck, but that ended in divorce after only six months. They had a son together.

Now a single mother of two young children, Martha found herself unemployed and looking for ways to escape her reality. She often bought romance magazines and watched romantic movies. In 1946, she got a job at the Pensacola Hospital for Children. In 1947, she placed an advertisement in the newspaper's lonely hearts section, leading her to meet Raymond Fernandez.

Martha Beck and Raymond Fernandez became known as the Lonely Hearts Killers. They were active between 1947 and 1949 and were accused of committing many murders. They first met when Fernandez responded to a personal ad placed by Beck. After meeting, Beck quickly left her children and traveled to New York to be with him.

In 1949, they committed their first known murder. Janet Fay, a 66-year-old woman, came to stay with Fernandez. When Beck found them together, she attacked Fay with a hammer. Fernandez then strangled Fay. They fled when Fay's family reported her missing.

Next, they moved to Michigan, where they met Delphine Downing, a young widow. Downing had a two-year-old daughter. When Downing became upset, Becky gave her sleeping pills to quiet her. The young girl started to cry, which made Beck angry. In a panic, Beck strangled the little girl but did not kill her. To keep Downing from becoming suspicious, Fernandez shot her.

Afterward, Beck drowned Downing's daughter in a basin of water. They buried both bodies in the basement of the house. Soon, neighbors noticed that Downing and her daughter were missing and contacted the police. On March 1, 1949, the police arrested Beck and Fernandez.

During the trial, Fernandez quickly confessed to the murders. However, both denied the many other murders they were accused of committing. They were extradited to New York to stand trial. The death penalty was still enforced there at the time. Eventually, they were convicted of Janet Fay’s murder. They received the death sentence and were executed in the electric chair at Sing Sing prison on March 8, 1951.