Yes, brothers Samuel and Richard Guzzino were the first cousins of Nicholas “Jumbo/Nicky” Guzzino Jr, who was born in 1941 in the Heights.
Sam and Richard’s dad was Phillip Guzzino (d.1956), while Phillip’s brother Nicholas Guzzino Sr (d. 1979) — operator of Oliver’s restaurant in Calumet City — was the father of Nick Jr. Nick Sr and Phillip were also brothers of Joe Guzzino, a *possible* LCN member who died in 1966. With longstanding relationships to the LaPortes and Rubertos, Joe Guzzino was a major gambling power in Cal City who was also named as the suspect in the 1926 murder of Girolamo “Jim” Lamberta, a presumed leader in the old Chicago Heights Family prior to its absorption into the Chicago Family. Worth noting also that the Guzzino name has long been prominent in the mafia back in their hometown of Caccamo.
It’s unclear to me who Nick Guzzino Jr’s mother was and he *may be* only half-Italian. His “mother” was a woman from Kentucky named Lorraine Nesmith, but Nick Sr only married her in 1947, so I don’t know if she was actually Nick Jr’s biological mother. Nick Sr clearly had a thing for “hillbilly” chicks, as he had been married at least twice before. In 1938 he made the papers for shooting and seriously wounding one of his previous wives, who he had only married a few months prior.
Nick Guzzino was an important associate of Dom Palermo, so it wouldn’t surprise me in the least if he had been involved in his cousin’s murder, but unlike the bungled Pilotto assassination attempt (where co-conspirator and Sam Guzzino’s son-in-law Daniel Bounds flipped), we haven’t had any informants discuss the Sam Guzzino murder (I also don’t recall seeing any intel in Sam Guzzino’s FBI file on suspects in his murder).
Nick Guzzino Sr:
A younger photo of Sam Guzzino:
A young Richard Guzzino:
I also have a photo of Nick Petrizzo an affiliate of Panzica who you mentioned. The source who shared the photo is a relation of Petrizzo - I placed him in Chicago Heights due to the newspaper reports, but maybe Grand Avenue is more realistic. 
