Lea-Plaza Sáenz was born in Santiago on 18 March 1912, the son of Alfredo Lea-Plaza Jencquel and Rosario Sáenz Montt.[1]
He married Emilia Concepción Molina Retamales in Valdivia on 28 June 1941; they had four children.[1]
He studied at the Liceo Alemán de Santiago, then studied law at the Universidad de Chile and the Pontificia Universidad Católica de Chile. He was sworn in as lawyer on 19 August 1942; his thesis was titled “El procedimiento de los delitos contra la seguridad interior del Estado”.[1]
He began working as secretary of the Minister of Lands and Colonization, Carlos Henríquez, in 1933. From 1930 to 1938, he served as inspector-conservator of the Civil Registry. He also taught Political Economy and Civic Education at the Instituto Salesiano. After 1939, he practiced law in Valdivia; he was member and counselor of the Valdivia Bar Association.[1]
He was a founding member in Valdivia of the Agrarian Labor Party, serving as president of the Provincial Assembly and Directory, and in 1954 joined the faction “Agrarian Labor Party Recuperacionista”. He presided over the Second National Assembly of the Party, held in Valdivia.[1]
He was elected Deputy for the 22nd Departamental Group (Valdivia, La Unión y Río Bueno) for the 1949–1953 term, and re-elected for 1953–1957. During his first term he served as substitute member on the Permanent Commissions on Interior Government; Foreign Relations; Economy and Commerce; Internal Police and Regulation; and was full member of the Commission on Constitution, Legislation and Justice. In 1952 he represented the Chamber of Deputies at the United Nations. During his second term he was part of the Permanent Commission on Finance (Hacienda).[1]
Outside politics, he belonged to the Fifth Company of Santiago Firefighters (joined 14 April 1930, later honorary member), was director of the “Society of Friends of Art”, and associated with the Club de la Unión and the Valdivia Lions Club.[1]
He died on 11 January 1974.[1]