Raymond Martinez Fernandez was born on December 17, 1914, in the Territory of Hawaii to Spanish parents. His family moved to Bridgeport, Connecticut, shortly after his birth. As a teenager, he went to Spain to work on his uncle's farm. While there, he married a local woman named Encarnación Robles, and together they had four children. However, he later abandoned them.

During World War II, Fernandez served in the Spanish merchant navy and the British intelligence services. After the war, he had a difficult time. After being released from a hospital, he stole some clothes. This act led to his imprisonment for a year. While he was in prison, his cellmate introduced him to the beliefs of voodoo and black magic. After learning these, Fernandez claimed that black magic gave him power and charm over women.

Raymond Fernandez and Martha Beck became known as the "Lonely Hearts Killers." They met through a personal ad placed by Beck and began a relationship. After a short visit, Fernandez returned to New York City, while Beck moved to prepare for their future together in Florida. When she lost her job, Beck left her children and moved to New York, where Fernandez enjoyed her attention and devotion.

In 1949, the couple committed three murders. Their first victim was 66-year-old Janet Fay, who was engaged to Fernandez. When Beck found Fay in bed with him, she attacked Fay with a hammer, and Fernandez strangled her. They fled after Fay disappeared, becoming suspicious of police interest in the case.

Next, they traveled to Wyoming Township, Michigan, where they met Delphine Downing, a 28-year-old widow with a two-year-old daughter. During their stay, Downing became agitated, and Fernandez gave her sleeping pills. When Downing's daughter cried, Beck panicked and strangled the child but did not kill her. To prevent Downing from becoming suspicious, Fernandez shot her. In a further fit of rage, Beck later drowned Downing's daughter. They buried the bodies in the basement of Downing's home.

Neighbors began to suspect something was wrong when the Downings went missing. Police arrived on March 1, 1949, and arrested Fernandez and Beck. Following their arrest, Fernandez confessed to the murders. They denied involvement in several more killings linked to them. After being extradited to New York, they were tried for the murder of Fay and sentenced to death. Both were executed by electric chair at Sing Sing prison on March 8, 1951.