It was a tragic mistake as Juan Carlos accidentally shot his younger brother, Infante Don Alfonso, who died as a result of the shooting.
Juan Carlos' discussion of his brother's death is featured in a documentary of the former King's life, "Yo, Juan Carlos, King of Spain, that was made more than five years ago. The film, which has already been seen in France, is based on an interview between Juan Carlos and French writer, Laurence Debray.
The film had been banned in Spain, but finally, Juan Carlos has agreed to its release.
Juan Carlos was very fond of Alfonsito, as he affectionately called his younger brother. "We were very close. I loved him very much ... I still miss him very much."
The death of Alfonsito left Juan Carlos severely depressed that took many years to overcome, as the guilt he felt for causing his brother's death was intense.
As a child he was unable to put down roots. "I was born in Rome and lived in Switzerland before settling in Portugal, there was no sense of nostalgia at home. We did have many friends and cousins to play with, we loved each other very much and we were close to our parents," King Juan Carlos said.
Juan Carlos had a "very special relationship" with both his parents, Juan and Mercedes, the Count and Countess of Barcelona. His father's death in 1993 was particularly painful. "It was a really hard moment, he was my most faithful ally. I buried him as a king, as he deserved it. He dedicated his entire life to Spain. He sacrificed himself for the good of the country, that is the greatness of the man and I was lucky he was my father."
He denies the reports that Francisco Franco was a mentor. He was only ten years old when he moved to Spain for his education. At ten he was "terrified" but "quite impressed" with the dictator. He had no choice but to accept the move to Spain, leaving his parents behind in Portugal.
"Franco was not my mentor, it was my father, despite the distance."