Marvin joined IEG after a successful career in the Central American Bank of Economic Integration in Tegucigalpa, Honduras, where he held positions such as Controller (Independent Oversight and Evaluation Authority), Executive Vice President, Chief Economist and Chief of Evaluation. Marvin also served as Vice-Minister of Finance for the Republic of Costa Rica, his native country.

He holds a PhD in Economics from Carleton University and Ottawa University in Canada, an MA in International Affairs from the Norman Paterson School of International Affairs in Canada, and a Lic. and a BA in Economics from the University of Costa Rica.