Harvey A. Marcelin was born on May 21, 1938, in Harlem, New York City. He was the only child of a shipping clerk and a seamstress. When Marcelin was young, his family moved to Washington Heights. He was raised in a relatively stable environment and was spoiled by his parents.

When he was ten years old, his father died. After this, Marcelin was raised by his mother alone. He went to kindergarten first and then attended a Catholic school run by the St. Aloysius Catholic Church in Harlem. While at this school, Marcelin reported experiencing abuse from the nuns, including being whipped and forced to eat expired food. These experiences caused him emotional and behavioral issues. By his teenage years, he started engaging in sexual behavior that was considered deviant.

Marcelin began cross-dressing in 1951 after going to a Halloween party. This led him to feel discomfort with his gender identity, known as gender dysphoria. At the age of 14, he was accused of attempting to sexually assault an 8-year-old girl. Not long after, in the summer of 1952, Marcelin was admitted to a psychiatric hospital for evaluation. The reports stated that he was truant, had committed theft, and engaged in sexual activities with both men and women. After his release, he went back to school and graduated in 1956, but soon returned to a life of crime.

In 1957, he was charged with burglary, convicted, and sent to county jail for several months. After being released, Marcelin lived with his mother and worked as a copy machine operator. He found it hard to keep a steady job because of his mental illness and drug problems. During his time in treatment, doctors found that he showed signs of chronic schizophrenia and had a paranoid personality. In 1962, he voluntarily sought treatment at Bellevue Hospital and stayed there for a week before being discharged to his wife's care.

In the early 1960s, Harvey A. Marcelin began a violent path that would lead to multiple murders over several decades. His first known victim was Jacqueline Bonds. On April 18, 1963, he shot Bonds in her apartment after an argument. After the shooting, she attempted to escape to her bedroom but fell into the living room, where she died from her injuries. Marcelin was arrested afterward and underwent a psychiatric evaluation, which determined he was sane to stand trial. He was found guilty of murder and sentenced to life in prison.

After serving over 20 years, Marcelin was paroled in 1984. Shortly after, he met Anna Miranda, a heroin addict and prostitute, in 1985. On October 29 of that year, they got into an argument, and he stabbed her to death. Afterward, he dismembered her body and disposed of the remains in various locations in Central Park. Marcelin was arrested when a neighbor reported seeing him carry bloodied trash bags. During questioning, he admitted to the murder but claimed it was in self-defense. He later pleaded guilty to manslaughter.

Marcelin continued to apply for parole for many years and was granted release again in 2019, at the age of 81. He changed his name to Marceline Harvey and began living in New York City. He met Susan Leyden, a 68-year-old woman, in late 2019. The two developed a relationship and started living together. However, in late February 2022, authorities allege that Marcelin killed Leyden, dismembered her body, and scattered it around New York City. After finding parts of Leyden's remains, police arrested Marcelin. His trial for her murder began in March 2024.