He didn't know, because Tessio didn't turn traitor until just after he died. Vito only knew that there would be a traitor, and that the traitor would be whoever tried to set up a 'peace meeting' between Michael and Barzini.
After Sonny's death, Don Corleone agrees to lend his political protection to the enterprise and forgive the other families for having his son killed. Although it initially appears that Don Philip Tattaglia is responsible for organizing the anti-Corleone alliance, Vito soon realizes that Barzini is the true mastermind.
How did Vito Corleone figure out it was Emilio Barzini who was behind the assassination of Sonny Corleone? Because Barzini showed his cards when he followed up on Phillip Tattaglia's comments about the politicians and judges the Corleones were connected to during the meeting of the Five Families.
Paulie has seemingly betrayed Vito—and thus the family—by selling him out. In The Godfather, this kind of betrayal is the worst of all sins. We see the matter discussed, in the Corleone family office, just before the viewer spends time in front of Clemenza's cozy abode.
Michael observed and Tessio was the one who approached him at Vito's funeral to ask about the meeting with Barzini. Tessio also spoke about 'arranging security' which made it even more obvious that Michael would be killed at this meeting and that Tessio was involved in this.
How did Vito Corleone know Tessio was the Traitor? Why Did Tessio Betray Michael Corleone?
How did Michael know Sal betrayed him?
In the novel, Tessio helps broker the summit shortly after Vito's death. In the film, Tessio approaches Michael at Vito's funeral about setting up the peace summit, Michael already anticipated the plot via his father's warning: whoever approached Michael about the peace summit would be the family traitor.
After telling Michael that he has never met Ola, Fredo later carelessly tells Geary that he had been to a nightclub with Ola. Michael overhears the conversation and realizes that Fredo betrayed him to Roth. He confronts Fredo, delivering the kiss of death.
A rat is another word for snitch or informant. These four rats betrayed the Corleone family: Salvatore “Sal” Tessio, Paulie Gatto, Fabrizio and Carlo Rizzi.
David Chase instead offered him the role of playing Paulie Gualtieri, Sirico agreed under the condition that his character would not "become a rat". Paulie begins the series as a soldier, later becoming a caporegime in the DiMeo crime family.
(The only member missing is Paulie, who's in jail on a gun charge and, unknown to Tony, making collect calls to Johnny Sack.) This thing of ours is supposed to be recession-proof, he reminds them, and things had better improve.
Luca Brasi is Don Vito Corleone's personal enforcer and the only man Vito himself fears. While slow-witted and brutish, Brasi is fiercely loyal with a reputation as a savage and remorseless killer.
Connie (who was unaware of her husband's role in Sonny's murder), hysterical after Carlo's death, blames Michael, denouncing him in front of his wife, Kay. In the novel, Connie quickly recovers from Carlo's demise, apparently relieved to be rid of an abusive, philandering husband.
Enraged, Sonny speeds towards Connie's apartment in Hell's Kitchen ahead of his bodyguards. At the Long Beach Causeway toll plaza, Barzini's men trap Sonny and shoot him to death. During a meeting with the other crime family dons to establish peace, Vito realizes that Barzini masterminded Sonny's murder.
The Corleone family are fictional characters in both the novels and the films created by Mario Puzo, first appearing in his 1969 novel, The Godfather. They are an organized crime family originating from the Sicilian town of Corleone, and based in New York City.
Clemenza stays a friend to Michael while Tessio decides Michael can't win and makes a deal with Barzini to assassinate him. The reason for Clemenza's loyalty is years of working together, making money, and protecting each other. Not just Vito but his family too.
Hours later, Michael confronts Rizzi, saying he knows Rizzi set Sonny up to be murdered. He assures Rizzi that his life will be spared, but that he is being exiled from the family. Rizzi, believing he is safe, confesses that he conspired with Barzini.
Jimmy Altieri's status as a rat in The Sopranos is still debated among fans due to conflicting evidence and Tony's suspicions. Tony's suspicions of Jimmy are supported by factors such as his quick release on bail, knowledge of forensic techniques, and suspicious behavior.
By The Sopranos season 6, Silvio remains loyal to his crew, but he's gunned down by Lupertazzi hitmen in "The Blue Comet." Tony learns that his right-hand man isn't expected to regain consciousness and then holds his hand during a hospital visit in The Sopranos series finale, "Made in America."
In fact, this became part of a Sopranos episode later when Tony was reproached by a boss for the shorts. What the mobster meant, of course, is that when you have that kind of a leadership position, you can't afford to look too casual to those that you are supposed to be leading. It's a lesson that's often forgotten.
Most noteworthy, the novel depicts Clemenza's fatal heart attack (mentioned in The Godfather Part II), and the many conspiracy theories that he had actually been murdered by the Rosato Brothers, former Corleone soldiers who had formed their own gang after a dispute over the future of the family.
In 1901, the local mafia chieftain, Don Ciccio, murders Vito's father Antonio when he refuses to pay him tribute. Paolo, Vito's older brother (presumably ret-conned as the one born in 1887), swears revenge, but Ciccio's men kill him too.
A rift grows between Pentangeli and Michael, however, that eventually results in Pentangeli betraying the family. Pentangeli's character was created in The Godfather Part II by Coppola and Puzo due to actor Richard Castellano not reprising his role as Clemenza in the sequel.
No, Fredo Corleone was not intellectually and socially deficient in the movie The Godfather. He was simply not as smart or as savvy as his brothers Michael and Sonny. This is evident early on in the movie when he gets caught up in a scam with Johnny Ola that nearly costs Michael his life.
Victor Rizzi was the son of Connie Corleone and Carlo Rizzi. He was at Anthony Corleone's first communion and seen with his brother Michael Rizzi coming in the door at Carmela Corleone's funeral. Victor was arrested in Reno for theft some time shortly before Anthony's first communion.
