John Patsalos was born on January 6, 1938, in New York City, New York. His parents were from Greece. When John was five years old, his mother decided to move him and his younger brother, George, to their grandmother's house. This was a significant change in their lives. Shortly after they moved, a tragic event occurred. Their father shot and killed their mother. As a result, he was convicted of manslaughter and sent to Sing Sing Prison. He was released on parole in 1953.

After their grandmother passed away, John and George had to move again. They were sent to the Bronx to live with their father. At this time, things were not stable for them. Their father faced child abuse charges, and both boys spent two weeks at the Youth House while waiting for a resolution. Eventually, they were released back into their father's care.

On August 25, 1967, John Patsalos shot and killed George Lincoln Rockwell, the leader of the American Nazi Party. Rockwell was in his car at a shopping center in Arlington, Virginia, when he was attacked. The weapon used was a Mauser pistol. Patsalos was arrested shortly after the shooting, about a mile away from the scene.

In December of the same year, Patsalos was convicted of first-degree murder. The prosecution asked for the death penalty because it was premeditated, but the jury recommended a lesser sentence. He was sentenced to 20 years in prison.

Patsalos remained free on bail while appealing his conviction. In 1969, he won a libel case against a party official who falsely accused him of stealing the gun used in the murder. However, his appeal to the Supreme Court of Virginia was denied, and he was sent to prison in 1970. His appeal to the U.S. Supreme Court was also rejected in 1972.

He was paroled in August 1975 after serving less than eight years of his sentence. In 1976, he faced additional legal trouble for trespassing and possession of marijuana. The trespassing charge was later dismissed, but he did violate his parole and received another six-year sentence.

In the 1970s, Patsalos began to distance himself from his past. He contributed to a Spanish-language newspaper and expressed regret about his former beliefs. He attempted to change back to his original name as part of this new path. By 2017, he was described as a supporter of Donald Trump and participated in online discussions regarding various political rallies.