Usually being the best and most successful in your field is a good thing. But in the case of Richard Kuklinski, nicknamed “The Iceman,” it’s absolutely horrifying. That’s because this dude killed people for a living, eventually becoming the busiest hitman in the mafia. Not only was he brutal, grotesque and immoral, but he excelled as an executioner of people in a society that revolved around corruption and violence. Forget Dexter. Kuklinski was not a small-screen fictional character but a real-life sociopath. For those who can stomach heinous violence, here’s more about Richard Kulinski’s mafia rise:

Abused kid becomes a prolific killer

Kuklinski didn’t create the East Coast mafia hitman job description. That role has always been part of the criminal underworld, with mob bosses continually keeping trusted hitmen on the books so they could do away with other mafioso who posed a threat. But he eventually became the busiest hitman, a dubious but hard-to-achieve distinction.

His preparation for the role started early and it’s kind of a sad story. Born in the Jersey City projects to immigrant parents in 1935, Kuklinski’s Polish father was both an alcoholic and a child abuser who beat his son senseless on more than one occasion (and was rumored to have killed Richard Kuklinski’s brother by pushing him down the stairs). His Irish immigrant mother also joined in, beating him with a broomstick until it broke in half. As psychologists will tell you, a leading reason someone becomes abusive is a childhood history of being abused, and Kulinski definitely had that background.

His early violent tendencies were creepy but were sort of textbook given his family background.  He tortured pets, for example, and bragged that he beat a man to death while he was still in his teens. Once he was old enough for romantic relationships, they became violent as well. He stabbed his second wife Barbara Pedrici in the back merely for mentioning that she wasn’t sure how well the relationship was going. So strong was his hold on her, though, that she still married him in 1961 and they stayed married until eight years after he went to prison. (Winona Ryder played Barbara in the 2012 movie The Iceman.)

The Iceman sets some records

Along with being a stereotypical domestic abuser, Kuklinski was a depraved killer and mafia hitman. He was massive, six-foot-four and 290 pounds with the shoulders of a linebacker and enormous hands. But he was no gentle giant, instead known for his hair-trigger temper, the type of guy who would kill a man over a minor annoyance.

He was distinct in other ways, too. For one, as well as making five figures on most hits, Kuklinski really enjoyed the killing process. He earned the nickname “The Iceman” because he liked to freeze bodies to thwart forensic attempts to pinpoint the time of death. Unlike most serial killers, he did switch up both the way he killed his victims and how he disposed of the bodies. His pro career began as early as 1950 when he was just 15. He was known to work as a hitman for both the Genovese and DeCavalcante crime families. The Gambino family would later hire him to do their dirty work, but as a freelancer, not a family member.

At age 18, he increased his stature with the depraved Gambino soldier Roy DeMeo by killing a random stranger on the street at DeMeo’s casual request. DeMeo probably didn’t realize at the time that Kuklinski actually enjoyed killing, whether for profit or to avenge perceived personal slights. According to his daughter Merrick, he killed her dog to punish her for coming home late from a date. And he once told she and her sister that if he ever killed her mother in a violent rage, he’d have to kill them, too, so as not to leave any witnesses. Her response: “I understand.”

Convicted of two murders, responsible for many more

Starting with his second marriage in 1961, Kuklinski lived a sort of triple life. While he was a mob killer, he also maintained the facade of a New Jersey father of three who lived in a middle-class home, planned trips to Disney World and made home movies. He was an usher at church on Sundays; he and his wife ate breakfast most days at the Seville a few miles from his comfortable neighborhood. The facade within the facade was his abuse of his wife while maintaining an appearance as half of a well-regarded suburban couple.

All the pretense blew up in Kuklinski’s face when an undercover sting finally caught up to him in 1986. Two murder convictions followed, and Kuklinski began serving two life sentences in 1988 (more time was added after he confessed to a third slaying).

Kuklinski was loquacious in prison, granting interviews right and left with people trying to figure him out. This included writers and psychiatrists, and each new interviewer seemed to draw a different body count claim from Kuklinski. The real number? Somewhere between 100 and 200, a mix of personal vendettas and mafia chores. He also took credit for teamster boss Jimmy Hoffa’s disappearance and then recanted his murder confession. He died in the same state he was born in, New Jersey, at age 71. Angry to the end, he claimed his rare inflammatory ailment was the result of poison. But true or not, this was one time Kuklinski was not able to murder the person he thought was trying to harm him. At least 100 other people were not lucky enough to escape his wrath.