SOMERVILLE, N.J. — It was a scenario right out of the movie “Goodfellas” — except the blood wasn’t fake, and neither was the corpse.

The death of John “Johnny Cokes” Lardiere, who was found shot to death in a motel parking lot 30 years ago next month, was the brutal manifestation of a code of conduct that has largely disappeared from organized crime circles, experts say.

The case returned to the forefront with the capture last Friday in New York City of reputed former Genovese family capo Michael Coppola, who disappeared in 1996 after a court ordered him to supply blood and saliva samples for DNA testing.

Through his lawyer, Mr. Coppola pleaded not guilty yesterday and was being held in lieu of $1 million cash bail in Somerset County Jail.

Lardiere’s fate was sealed when he got into an altercation with Ralph “Blackie” Napoli, a member of Philadelphia’s Bruno/Scarfo crime family, and slapped Mr. Napoli in the face, according to a former head of the state attorney general’s organized crime unit, Robert Buccino. At the time, Lardiere and Mr. Napoli were being held in New Jersey for refusing to cooperate with a state investigation into organized crime.

“Not only was he a ‘made’ man, he was a capo,” Mr. Buccino said, referring to Mr. Napoli. “‘Cokes’ was in the Genovese family, and so it became their responsibility.”

That meant Lardiere had to be killed by one of his fellow Genovese members, much as the fictional character played by Joe Pesci in “Goodfellas” was killed because he had killed a “made” member of another crime family without permission.

“Back in those days, there were rules that had to be abided by,” an expert on the Philadelphia mob and author of several books on organized crime, George Anastasia, said. “You weren’t supposed to hit a made guy. It was a sign of disrespect. If you raised your hands to another made guy, the punishment was death.

“Those rules have all but gone by the boards,” Mr. Anastasia added. “Today, anything goes.”

According to state and federal authorities, Mr. Coppola waited until Lardiere was released for an Easter furlough and had checked into the Red Bull Inn in Bridgewater, then pumped five bullets into him as he went to his car to get his luggage.

An arrest warrant was issued for Mr. Coppola in 1996 three weeks after the court order for DNA samples. Authorities say a key break in the case came when mob turncoat Thomas Ricciardi identified Mr. Coppola as the killer. Mr. Ricciardi is expected to be a witness if the case goes to trial.

Prosecutors asked for $20 million bail, citing Mr. Coppola’s “obvious abhorrence for the rule of law and justice” and significant risk of flight.