Fidel Castro’s eldest son Fidel Ángel Castro Díaz-Balart, also known as ‘Fidelito’ is dead.

The 68-year-old nuclear physicist was the oldest son of former Cuban President Fidel Castro. He died on Thursday, Cuban state media reported.

Fidelito had been treated for depression for several months before he finally committed suicide NYTimes reports.

At the time of his death, he was a science adviser to Cuba’s Council of State and vice president of the Academy of Sciences of Cuba.

He studied in the Soviet Union, and was placed in charge of Cuba’s nuclear power program for a time, until he had a falling out with his father.

He had three children with Natasha Smirnova, whom he met in Russia. After divorcing Smirnova, he married María Victoria Barreiro from Cuba.

He was the only son of the former president and his first wife, Mirta Díaz-Balart.

He once told an interviewer that he never had political ambitions. “All my career has been as a scientist,” he said in a 2013 television interview with the Russian government-funded station RT.

His father, Fidel, died over a year ago, in November 2016, at age 90. His death came 9 months after his older brother Ramón died at the age of 91.

Fidel Castro was cremated on November 26, 2016, and after nine days of public mourning, his ashes were entombed in the Santa Ifigenia Cemetery in Santiago de Cuba.

Mr. Castro Díaz-Balart’s early childhood was marked by a bitter custody battle between his parents, who divorced in 1955 when he was 6.

The year after, when both of Mr. Castro Díaz-Balart’s parents were in Mexico, his father arranged for his son to visit him for two weeks. At the end of the visit, Mr. Castro placed Fidelito with a friend and sailed to Cuba with fellow rebels on the yacht Granma to begin his guerrilla campaign against the government.

To reclaim her son, Ms. Díaz-Balart, with the help of her family and the Cuban Embassy in Mexico City, hired professional kidnappers who ambushed the boy and his guardians in a park. Reunited with her son, she took him to New York for a year. But after Mr. Castro came to power in 1959, he persuaded his former wife to send their son back to Cuba.

As an adolescent, he said, he had little contact with his father. “It is no secret that in the years of my adolescence and youth, Cuba was going through a very difficult situation,” he said, referring to the era that included the American-backed Bay of Pigs invasion and the Cuban missile crisis.