Roy DeMeo was born in 1942 in New York City. His father and mother were Italian immigrants and they lived on the same block as mafia boss Joseph Profaci.

When Roy was a teenager he started a loan sharking business, which proved to be quite successful. He dropped out of high school when he was 18 in order to focus on his criminal activities and take things to a higher level.

Sometime in the early 1960s, he met John Gotti, another notorious criminal, and they worked together on several rackets. Soon Roy found himself involved in stealing cars and pornography. He also married in the 60s and fathered three children with his wife.

Roy's first known murder came in 1974, when he was 32 years old. He suspected that one of the men involved in his car theft ring was an informant and he shot him. Roy seemed to enjoy the power of murder and began killing anyone else he suspected of being a police informant or anyone that managed to get in his way. He also started performing hits for money, making himself a well known hitman in the underworld.

By the late 1970s, Roy had built a solid crew to work with him. The gang was known as the Gemini Crew since they hung out at the Gemini Club in Brooklyn. The members included Richard "Iceman" Kuklinski, Chris Rosenberg, Joseph Guglielmo, Anthony Senter, Henry Borelli, and Joey Testa.

The gang often performed hits as a group by getting the victim to come to the club and teaming up on them once they entered. Having been a butcher's apprentice in his younger years, Roy brought to the group a knowledge of butchering meat and applied it to the gang's victims. The technique usually consisted of allowing bodies to bleed dry in the bathtub, then chopping them into pieces to be disposed of in well concealed areas.

The crew did not hesitate to kill anyone, even women. At one point they killed a five-member group of Cuban drug dealers just to rip them off. Sometimes bodies were dumped in obvious places so they could send a message across to the appropriate people.

After years of working for the mafia, Roy was finally "made" by the Gambino family, led by Paul Castellano. He continued performing hits, although not as frequently since he now had more responsibilities as a made mafioso.

In the early 1980s, the FBI began closing in on the Gemini Crew after noticing that many murder victims had been seen entering the club or meeting with Roy before disappearing. On January 10, 1983, Roy was called to a meeting where he was whacked to protect the rest of the family. His body was found riddled with bullets and stuffed in the trunk of his own car on January 18th.

After Roy's death, the Gemini Crew was arrested and brought up on formal charges. The FBI succeeded in having the entire crew convicted of various offenses, including 25 murders. Paul Castellano was charged with ordering the hit on Roy DeMeo, but he was killed before the trial.