Frank Sinatra Jr., the son of the well-known artist who carried on his famous father Frank Sinatra’s legacy, died of heart attack on Wednesday, said manager Andrea Kauffman. Sinatra took his last breath at Dayton Beach, Florida, hospital. Reports reveal that he was on tour in Dayton Beach.

Sinatra Jr. was 72 and he held his own successful music career.

According to CNN, singer Nancy Sinatra posted on her Facebook page that her brother died of heart attack.

“Sleep warm, Frankie…,” she wrote down.

As noted by News, the statement said the family grieves over the unfortunate passing of their son, brother, father, and uncle. No other details were provided.

Sinatra Jr. was the son of senior Sinatra’s first wife, Nancy Barbato Sinatra, and the younger brother of Nancy Sinatra. Nancy also had a booming musical career of her own.

Sinatra Jr. grew up watching his father performing on the stage and followed him into music as a teenager. Frank Sinatra Sr. died of a cardiac arrest on May 14, 1998, at 82. Even after his father’s death, Sinatra Jr. was able to keep a link to his father’s music, by performing the great singer’s songs and arrangements on trips and in particular in Las Vegas.

In his word, “Since my father’s death, a lot of people have made it clear that they’re not ready to give up the music.”.

Sinatra Jr. was kidnapped by three men in 1963 when he was just 19. Sources say, these three kidnapped him at gunpoint from a Lake Tahoe hotel. He came back safely after two days when his family paid $US240, 000 ($A317, 986) for his release. Later on, it was found out that a high school friend of Nancy Sinatra, named Barry Keenan, was the mastermind behind such plan. Two other suspects Johnny Irwin and Joe Amsler along with Barry were also arrested and convicted of conspiracy and kidnapping.