Robert Prongay's story gets more confusing the longer it's told, but it all begins with prolific serial killer and suspected mob hitman Richard Kuklinski.

Nicknamed "The Ice Man" because he masked his victims' time of death by freezing their corpses, Kuklinski claimed to have killed more than 100 people on behalf of New York's five mob families - and he claimed learning his skills from a Special Forces veteran.

Kuklinski was only convicted of five murders, but that was enough to send him to prison for the rest of his life. These victims were petty drug and porn dealers in the mid-1980s.

In one of those killings, he used a burger containing cyanide, a killing technique he learned from a man he describes as a special forces veteran turned ice cream man, Robert Prongay.

“He taught me a lot,” Kuklinski once said. "But he was extremely crazy...He would go around these neighborhoods and sell ice cream to the kids, then maybe kill one of their fathers."

Kuklinski was known as "The Iceman" by law enforcement and Prongay was referred to as "Mister Softee". According to Kuklinski, the two men met at a New Jersey motel while stalking the same target. They boiled down and realized they were both hitmen. Prongay told Kuklinski that he was an army special forces veteran, trained in the use of explosives and poisons.

According to Kuklinski, Prongay used his ice cream truck as a surveillance van to track potential victims, whom he killed using cyanide spray and remotely detonated grenades. It was from Prongay that Kuklinski says he learned to freeze bodies to mask the time of death.

Not much is known about the real Prongay. Kuklinski claimed to have a very firm moral code when it came to killing. He could kill anyone without feeling anything at all, but he wouldn't kill innocent women and children.

The Iceman claimed that Mister Softee asked Kuklinski to kill his wife and young son for him, which Kuklinski refused. When Prongay started talking about poisoning an entire tank just to kill a family, Kuklinski shot him dead.

The only evidence of Prongay's existence and the possibility that he knew Kuklinski is that an ice cream man named Robert Prongay was killed in his ice cream truck with two bullets to the chest.

On August 9, 1984, his body was found hanging from the side of his ice cream truck. It turns out the real Prongay was on trial in New Jersey for blowing up his ex-wife's house and making terrorist threats against his ex-wife and son.

Prior to assassinating Prongay, Iceman and Mister Softee teamed up a few times. A 2001 HBO documentary found old film reels of Prongay and called him an "army demolitions expert", a claim verified by Paul Smith of the New Jersey Organized Crime Bureau.

"It's our opinion," Smith told HBO, "that the friendship led Richard Kuklinski to learn a lot about killings with different types of chemicals, including cyanide."

In fact, Kuklinski made a lot of claims about himself and his famous shots. He was convicted of killing the members of a small burglary gang he led in New Jersey, as well as one of his cyanide suppliers.

Statements from the people he worked for and murdered make his resume one of the most prolific hitmen in American Mafia history. If Kuklinski is to be believed, he was recruited by Gambino capo Roy DeMeo, who gave Kuklinski his death orders.

Kuklinski claimed responsibility for the murder of NYPD Detective Peter Calabro, a murder for which Gambino underboss Sammy "The Bull" Gravano has also been charged. The Iceman also claimed Roy DeMeo's death and claimed to be involved in John Gotti's famous stunt on Gambino boss Paul Castellano. The only mob hit that law enforcement has actually linked to Kuklinski is Calabro.

Kuklinski claimed to have killed some 100 to 250 people between 1948 and 1986, but his claims varied dramatically over the following years, with some unverifiable and others revealed to be complete fabrications (he claimed to have killed the famously missing Jimmy Hoffa, for example).

Renowned Mafia writers and historians claim to have never heard of a hitman named Kuklinski.

If Kuklinski's claims are true, he would be the most prolific serial killer/hitman in American history.