LAS VEGAS >> A mob museum slated to open soon in Las Vegas will trace Hollywood’s portrayal of mobsters from the birth of the silver screen in a violence-fraught exhibit that organizers said is not intended for children.

Screenwriter Nicolas Pileggi, who wrote the book “Wiseguy” and then adapted it into the Martin Scorsese film “Goodfellas,” told The Associated Press that he will help usher in the exhibit when the National Museum of Organized Crime and Law Enforcement opens in Las Vegas next month. Pileggi will appear in a five-minute documentary on the mob and pop culture that will be shown near the end of the museum tour.

The film, part of an exhibit called “The Myth of the Mob,” will attempt to explain why so many people are fascinated with organized crime. The exhibit will also feature costumes from mobster-centric TV shows and movies, including “The Sopranos.”

“Just because you are depicting something ugly, it doesn’t mean you are honoring it,” Pileggi said. “I don’t know too many gangster movies where the gangster wins in the end. These are tales of morality and that is the key to them.”

The downtown Las Vegas museum will open at a former courthouse where a famous mob hearing that helped expose organized crime to ordinary Americans was held in 1950. It is expected to feature gangster artifacts, including the wall from Chicago’s St. Valentine’s Day massacre, the only gun recovered at the mass shooting and the barber chair where hit man Albert Anastasia’s life came to an end in 1957.

Dennis Barrie, the museum’s director, said he interviewed Pileggi for up to three hours to create the five-minute film on the history of gangster flicks. Barrie said he wants museum-goers to explore whether popular movies glamourize mob culture, or get it right.

“I don’t think it’s a kids’ museum,” Barrie said. “This is a pretty brutal world and it comes across in the museum.”

Pileggi, whose parents were Italian immigrants, said he was attracted to mob stories as a young man because he wanted to know why some people in his neighborhood were drawn to organized crimes, while others shunned it.

“I don’t think they are the worst people in the world,” Pileggi said. “I think they are fascinating.”

Pileggi began his writing career as an Associated Press crime reporter. He received an Oscar nomination for “Goodfellas” and teamed up with Scorsese again for the Las Vegas crime-opus “Casino” in 1995. He said the movies are “unbelievably realistic.”

Pileggi said former Las Vegas Mayor Oscar Goodman asked him to get involved with the museum. Goodman, a former mob lawyer who came up with the idea of the museum, provided Pileggi with facts and insight when he was writing “Casino” and had a brief cameo in the movie.

“Who knows it better than Nick Pileggi?” Goodman said. “When you have his stamp of approval on these kinds of exhibits, it takes on a certain sense of reality as well as legitimacy.”

The $42 million museum will be the second gangster-focused attraction to open in Las Vegas in the past year.

The Tropicana casino and hotel on the Las Vegas Strip unveiled its interactive “Mob Experience” attraction in March. The venue is undergoing a renovation after a brutal start. Attendance was sluggish from the beginning, and then its developer, Jay Bloom, was forced to resign amid multiple lawsuits over unpaid bills, said Spence Johnston, a Mob Experience spokesman.

Goodman said the organized crime museum will have a more successful launch because its collection will focus on history instead of entertainment.

“I was interested in having a real museum with real culture,” he said. “This is not a gimmick.”