[greggh]

Multiple articles and interviews have said it was the Sicilian Mafia / La Cosa Nostra.

"The Five Families - the Bonanno, Colombo, Gambino, Genovese and Lucchese - have ruled the city's Italian American mafia since 1931."

"The Five Families are part of the larger American-Sicilian mafia operation known as La Cosa Nostra"

https://www.bbc.com/news/articles/cpv1rkxjyyno

[daseiner1]

The Sicilian Mafia (La Cosa Nostra) refers exclusively to the mafia on the island of Sicily, not the Mob which traces its lineage back to Sicilian immigrants.

It's being said because the Five Families was erroneously conflated with Cosa Nostra in the original press conference by one of the representatives of law enforcement.