After a career as a combat pilot, President Salvador Allende named him commander-in-chief of the Air Force on August 17, 1973, disregarding the established basis of seniority.

[citation needed] However, Leigh was the first to sign the coup document, drafted by Vice Admiral José Toribio Merino, to depose Allende.

"[citation needed] It was on his personal orders, he disclosed later, that the Air Force bombarded and heavily damaged the presidential palace to put down the resistance by Allende and a small group of his followers.

He condemns Chile, but at the same time he wants closer relations with a dictatorship like Castro's in Cuba, that had led an authoritarian regime for 18 years.

He was heavily influenced by the Egyptian model being built by Anwar Sadat (he was a close friend of Hosni Mubarak, the Egyptian Air Force Chief, since 1971) of a mixed economy based on free market principles but a strong state presence in heavy industry and a strong state regulation over imports and the financial speculation market.

Leigh was detained by a judge investigating his role in the disappearance of twelve communist leaders, but the Supreme Court of Chile ordered his release by virtue of the Law of Amnesty.

On March 21, 1990, members of the leftist guerrilla group, the Manuel Rodríguez Patriotic Front,[2] broke into Leigh's office and opened fire at him.