In Frank Sinatra and the Mafia Murders, Mike Rothmiller and Douglas Thompson draw on previously secret Los Angeles Police intelligence files, a cache of FBI documents released to the authors in 2021 and extensive interviews with prime sources, including many who worked with Frank Sinatra and many more who tracked his long and fatal association with the American Mafia, notably his ongoing connection, after his original godfather was assassinated: Sam 'Momo' Giancana, who shared a lover with President John F. Kennedy.

Sixteen days after the assassination of John F. Kennedy on 30 November 1963, nineteen-year-old Frank Sinatra Jr. was kidnapped at gunpoint from his hotel room in Lake Tahoe, Nevada. A $240,000 ransom was demanded from his father. While the FBI and Nevada and California law-enforcement agencies sprang into action, Frank secretly contacted his Mafia friends for help. The Mafia believed they could free young Frank much more quickly through their underworld connections. Some of those they questioned died.

Revealed here as never before is the extent to which Sinatra was adopted by the Mafia. They promoted his career and 'watched his back' and, in return, Sinatra danced to their tune. New information disclosed here shows that Sinatra also offered to spy for the CIA. Inside sources say Sinatra wanted the CIA to intercede to stop an investigation into his gaming licence in Las Vegas. But the CIA declined because they were already working with the Mob and were concerned Sinatra would learn of the Mafia's connection to the CIA and leak it.