Juan Reinaldo Sanchez, who served as Cuban leader Fidel Castro's bodyguard for 17 years, died earlier this week in Miami, the company that published his book said. He was 66.
Sanchez died on Monday, Spanish publisher Ediciones Peninsula said in a statement.
The former Castro bodyguard and French journalist Axel Gylden wrote "La cara oculta de Fidel Castro," which came out in 2014 and provided a firsthand account of the Cuban leader's public and private lives.
Sanchez, who held the rank of lieutenant colonel and was with Castro on a daily basis from 1977 to 1994, described the Cuban leader's life of "luxury and comfort" hidden behind a facade of "false austerity."
Sanchez, born in Havana in 1949, was imprisoned after retiring from Castro's security detail.
He was released from prison in 1996 and tried to escape from the island at least 10 times, finally making it out in 2008.
Sanchez wrote about Castro's lifestyle and possessions, which include about 20 luxury homes across Cuba, a yacht called the Aquarama II and a vacation home in Cayo Piedra, a small island off southeast Cuba that is a "paradise for millionaires."
Sanchez said he made the mistake of protecting the life "of a man ... dominated by the fever of absolute power and disrespect" for the Cuban people.