Fidel “Fidelito” Castro Diaz-Balart, eldest son of former Cuban president Fidel Castro’s, died by suicide on Thursday, according to Cuban media. The 68-year-old suffered from “profound depression” that led him to seek treatment, particularly in recent months. Fidelito was the only child born of his controversial father and Castro’s former wife Mirta Diaz-Balart’s relationship.  

Fidelito is also remembered as the most visible of his siblings. A polyglot nuclear scientist who was educated in the former Soviet Union, he briefly led Cuba’s nuclear program, before his father terminated him. Once Raul Castro, his uncle, assumed the Cuban presidency in 2008, Castro Diaz-Balart became the country’s scientific adviser and re-entered the public eye.

Jonathan Benjamin-Alvarado, a professor of foreign policy, Latin American studies and international relations at University of Nebraska in Omaha told Reuters that Fidelito helped him decades ago on a book about Cuba’s nuclear program. Benjamin-Alvarado added that Fidelito’s scientific advising position was likely more for appearances than for substantive policy change on the island country. 

“He had written extensively on Cuba’s need for developing renewable energy resources,” Benjamin-Alvarado said. “And yet almost all efforts by the Cuban government were geared to maintaining the status quo of oil dependency.” He continued. “I imagine that was disappointing for him.”