Old Story Abot Sacco&Vanzetti Framed (Ever Heard It)?

Many years ago, I read a book by a Boston gangster/Mafia guy named Vincent Theresa. The book was called “My Life In the Mafia”-sort of a prison autobiography.
Anyway, in the book, Theresa made the claim that the Italian anarchists Sacco and Vanzetti did not murder a payroll guard (for which they were tried, convicted and executed).
This Theresa claimed that the robbery was actually carried out by a local Mafia gangster, who arranged the frame-up of the two anarchists.
This man was still alive in the 1970’s, and told the story to Theresa.
I have never read anything about this from any other source-I cannot even locate Theresa’s book (none of the local libraries have it).
Anybody know more about this?

Like in the movie, Jerry and Tom, I can’t help but wonder if claims made by various ‘made men’ about notorious crimes aren’t for bragging rights, or to actually deflect attention from something they find ‘to close to home’.

(In Jerry and Tom an older ‘hit man’ divulges details about the Kennedy assassination, the characters were portrayed as believing the yarn, but the viewers of the movie were clearly not expected to buy in to it)

If any claim is made, like the interesting one in this thread, the claimant will have to reveal information known only to the killer and the police who investigated to confirm.

It is widely (although not universally) accepted that Sacco and Vanzetti were, in fact, innocent, and were framed, or, at the least, denied a fair trial, for political reasons.