Ernest Martin Ingenito was born on May 27, 1924, in Wildwood, New Jersey, to Ernest and Helen Ingenito. He was the eldest of three children in a family of Italian descent. The family frequently moved between Wildwood and Philadelphia, and his parents separated when he was thirteen. Ingenito's early life was troubled; he was first caught stealing at age ten and sent to a reformatory at fourteen. He continued to have run-ins with the law and spent time in and out of reformatories until he was paroled to live with his mother.

At seventeen, Ingenito married sixteen-year-old Doris Breslin, who soon became pregnant and gave birth to their daughter, Dorothy. The marriage was reportedly abusive. During World War II, Ingenito was drafted into the U.S. Army and stationed at Fort Belvoir in Virginia. He was dishonorably discharged in 1946 after being court-martialed twice—once for going AWOL and once for striking two superior officers. He served two years of an eight-year sentence at Green Haven Correctional Facility.

After his release, Ingenito divorced Doris and married twenty-one-year-old Theresa Mazzoli. They moved in with her family on a farm in Franklin Township, New Jersey, and had two sons. Initially, the marriage seemed stable, but tensions grew, especially with his mother-in-law, Pearl. Suspicions of infidelity led to Ingenito being expelled from the family home. He moved in with friends and began collecting firearms, practicing target shooting, and purchasing ammunition.

On the evening of November 17, 1950, at around 8 p.m., Ernest Ingenito armed himself with multiple firearms and drove to the Mazzoli family home. He confronted his wife, Theresa, demanding to see their children. When her father, Michael Mazzoli, intervened, Ingenito shot and killed him. He then shot Theresa in the stomach and shoulder as she attempted to flee.

Ingenito pursued his mother-in-law, Pearl Mazzoli, who had fled across the street to her parents' home. There, he shot and killed her mother, Theresa Pioppi, and her pregnant sister, Marion Pioppi. He also wounded nine-year-old Jeannie Pioppi. Pearl, attempting to hide in a closet, was found and killed by Ingenito. Additionally, he killed John Pioppi, Pearl's brother, who had tried to stop him with a knife.

Continuing his spree, Ingenito drove to Minotola, New Jersey, to the home of Theresa's aunt and uncle, Frank and Hilda Mazzoli. He shot both in front of their two young children; both survived their injuries. Ingenito was arrested by New Jersey State Police shortly after the shootings. Although he confessed during questioning, he refused to sign a written statement.

In 1951, Ingenito was convicted of first-degree murder for the killing of Pearl Mazzoli and sentenced to life imprisonment. Five years later, he pleaded no contest to four additional murder charges and received concurrent life sentences. Due to New Jersey laws at the time, he was eligible for parole and was released in 1974.

In 1994, Ingenito was arrested and convicted on 29 counts of sexual assault involving the daughter of his girlfriend, crimes that occurred over six years. He was sentenced to 50 years in prison. Ernest Ingenito died of heart failure on October 7, 1995, while incarcerated at New Jersey State Prison in Trenton.