Mr Marzo is presently the Secretary-General of the Brazilian-Argentine Agency for Accounting and Control of Nuclear Materials (ABACC), which is responsible for applying safeguards in Argentina and Brazil.
From September 2014 to June 2016, he was a Research Professor at University of Massachusetts Lowell.
He was the Director of the Division of Operations A, Department of Safeguards of the International Atomic Energy Agency (IAEA) from 2008 to 2014.
Mr. Marzo was the first Senior Officer for Planning and Evaluation of ABACC from 1992 to 2006.
As Director of the Safeguards Division at the Brazilian Nuclear Energy Commission from 1983 to 1992, Mr. Marzo led the Brazilian technical delegation to the negotiation of the Agreement between Argentina and Brazil for the Exclusively Peaceful Use of Nuclear Energy (Bilateral Agreement) and the Agreement between Argentina, Brazil, ABACC and the IAEA for the Application of Safeguards (Quadripartite Agreement) .He was member of the Standing Advisory Group on Safeguards Implementation (SAGSI) of the IAEA.

He has published 60+ papers in the areas of nuclear non-proliferation, safeguards and security.

Mr. Marzo holds a PhD in nuclear engineering from the University of Karlsruhe, Germany, in 1981.