Leo was born in Rio de Janeiro, Brazil, in 1944. In 1968, having acquired an engineering degree, he was a member of the Leftist student movement. He had to leave his country in 1971 to escape from the military dictatorship. In 1974, he was back in Brazil and decided to devote himself to drawing. When Leo discovered European graphic novels, he decided to try his luck in France and settled in Paris in 1981. He started drawing stories in Okapi magazine in 1986, and in 1989, he illustrated an album about the life of Gandhi, published by Editions Centurion. His work drew the attention of scriptwriter Rodolphe, who entrusted him with the drawings for his new series, Trent. Leo's career was established. In 1993, he launched his own series: Aldebaran, a science fiction saga of which he is also the scriptwriter.