Sinatra was kidnapped at the age of 19, on December 8, 1963, at Harrah’s Lake Tahoe (room 417). He was released two days later after his father paid the $240,000 ransom demanded by the kidnappers (equivalent to $2,000,000 in 2019). Barry Keenan, Johnny Irwin, and Joe Amsler were soon captured, prosecuted for kidnapping, convicted, and sentenced to long prison terms, of which they served only small portions. Mastermind Keenan was later adjudged to have been legally insane at the time of the crime and hence not legally responsible for his actions. Famed attorney Gladys Root represented Johnny Irwin.

Sinatra appeared in the Sammy Davis Jr. drama A Man Called Adam in 1966. He also played a deputy district attorney, named Gino Bardi, on the television crime drama Adam-12, in the episode titled “Clinic on 18th Street” (originally broadcast on March 13, 1974). This episode was an edited television pilot for a Mark VII Limited series that was not sold. His other acting credits included roles in Aru heishi no kake (1970) with Dale Robertson, Code Name Zebra (1987) opposite James Mitchum, and Hollywood Homicide (2003) with Harrison Ford and Josh Hartnett.

The National Archives now houses a 15-minute song and monologue composed by Sinatra in 1976, Over the Land. It evokes the memory of the nation’s flag and the nation’s experiences with the flag since the War of 1812.

Starting in 1988, at his father’s request, Sinatra placed his career on hold in order to act as his father’s musical director and conductor. Poet/vocalist Rod McKuen said:

In 1989, Sinatra sang “Wedding Vows in Vegas” on the Was (Not Was) album, What Up, Dog?, and performed the song live with the band on Late Night with David Letterman on March 23, 1989.

Sinatra married Cynthia McMurry on October 18, 1998; they divorced on January 7, 2000. He had one son Michael, from a previous relationship.

In 2006, Sinatra released the album That Face!, including the songs “You’ll Never Know” and the self-penned song “Spice.”

Sinatra underwent surgery for prostate cancer in January 2006.

He returned in a 2008 episode, “Tales of a Third Grade Nothing” (Season 8, Episode 6), wherein he sang with Brian again, with Stewie returning as a sideline investor supporting the duo. A third episode featuring Sinatra, “Bookie of the Year” (Season 15, Episode 2), aired posthumously on October 2, 2016 and was dedicated to his memory. This was his final appearance recorded.

On August 17, 2015, Sinatra sang “The Star-Spangled Banner” at Yankee Stadium.{https://www.youtube.com/watch?v=avMEykA3kx4}

On March 16, 2016, the Sinatra family released a statement to the Associated Press that Sinatra had died unexpectedly of cardiac arrest while on tour in Daytona Beach, Florida, at the age of 72.