[1][3] Kuklinski's modus operandi was to lure men to clandestine meetings with the promise of lucrative business deals then kill them and steal their money.

[4] Eventually, Kuklinski came to the attention of law enforcement when an investigation into his burglary gang linked him to several murders since he was the last person to have seen five missing men alive.

[5] He said he participated in several famous Mafia killings, including the disappearance and presumed murder of Teamsters' president Jimmy Hoffa.

His mother was Anna Cecilia McNally (1911–1972) from Harsimus,[13] a devoutly Catholic first-generation Irish American who worked in a meat-packing plant.

Kuklinski also discovered a lucrative market for tapes of pornographic films, making copies and distributing pornography a regular source of income.

[27] Malliband's body was discovered a week later on February 5, 1980 after Kuklinski had placed it in a 55-gallon drum and left it near the Chemitex chemical plant in Jersey City.

"[30] On April 29, 1982, Kuklinski met Paul Hoffman, a 51-year-old pharmacist who occasionally browsed "the store" in Paterson, New Jersey, a storefront with a back room holding a wide variety of stolen items for sale.

Hoffman hoped to make a big profit by purchasing stolen Tagamet, a popular drug to treat peptic ulcers, to re-sell through his pharmacy.

[28] According to forensic pathologist Michael Baden, Smith's death would probably have been attributed to something non-homicidal in nature, such as a drug overdose, if Kuklinski had relied solely on the poison.

[1] Medical examiners listed Deppner's cause of death as "undetermined," although they noted pinkish spots on his skin, a possible sign of cyanide poisoning.

Investigators guessed that Deppner had already been incapacitated, such as by poison, because the partially-eaten corpse had no defensive wounds and healthy adult men are rarely killed by strangulation.

On September 25, 1983, the body of 50-year-old Louis Masgay was discovered near a town park near Clausland Mountain Road in Orangetown, New York, with a bullet hole in the back of his head.

The Rockland County medical examiner found ice crystals inside the body on a warm September day.

[5][39] He alleged he used multiple ways to kill people, including a crossbow, ice picks, a bomb attached to a remote controlled toy, firearms, grenades, as well as cyanide solution spray he considered to be his favorite.

According to Jerry Capeci, "[Philip Carlo] claims the Iceman killed Paul Castellano, Carmine Galante and Jimmy Hoffa, along with Roy DeMeo and about 200 others.

[50] Former Colombo family capo Michael Franzese called Kuklinski a "pathological liar" and said, "I spent 25 years in that life, on the street.

[52] Prongay was murdered on August 10, 1984, shot multiple times in the head, and was subsequently discovered in his Mister Softee ice cream truck in a garage he rented in North Bergen, New Jersey.

[3] In 1993, in response to his claims, Hudson County Prosecutor said new charges against Kuklinski were possible since the Prongay murder was still an open investigation, and they would assess whether there was enough evidence to prosecute him.

Kuklinski claimed he killed 42-year-old Gambino crime family soldier Roy DeMeo in an interview for the 1993 book The Iceman: The True Story of a Cold-Blooded Killer by Anthony Bruno.

[57] In his 2001 HBO interview, Kuklinski confessed to killing 36-year-old NYPD auto crimes detective Peter Calabro, who was ambushed and shot dead by an unknown gunman in Saddle River, New Jersey on March 14, 1980.

[58] His wife Carmella had drowned under mysterious circumstances three years earlier, and members of her family believed Calabro was responsible.

At the time, his murder was thought by law enforcement officials to be revenge either carried out or arranged by his deceased wife's relatives.

[5] Describing the murder, Kuklinski said he parked his van on the side of a narrow road, forcing other drivers to slow to pass.

[63][62] Gravano denied any involvement in Calabro's death and rejected a plea bargain, under which, he would receive no additional jail time if he confessed to the crime and informed on all his accomplices.

[66] In his 2001 HBO interview, Secrets of a Mafia Hitman, Kuklinski said he knew who killed 62-year-old former Teamsters union president Jimmy Hoffa.

[10][40] Deputy Chief Bob Buccino, who worked on the Kuklinski case, said: "They took a body from Detroit, where they have one of the biggest lakes in the world, and drove it all the way back to New Jersey?

"[10] Anthony Bruno said he investigated Kuklinski's alleged involvement in Hoffa's disappearance but felt "[his] story didn't check out."

[6] A joint task force of law enforcement officials titled "Operation Iceman" was created between the New Jersey Attorney General's office and the Bureau of Alcohol, Tobacco, and Firearms (ATF) dedicated to arresting and convicting Kuklinski.

Law enforcement officials said Kuklinski had large sums of money in Swiss bank accounts and a reservation on a flight to that country.

At a press conference, New Jersey state Attorney General W. Cary Edwards characterized the motive for the murders as "profit" and said, ″He set individuals up for business deals, they disappeared, and the money ended up in his hands.″[2] At trial, Kuklinski's former associates, including Percy House and Barbara Deppner, gave evidence against him, as did ATF Special Agent Polifrone.