Born on April 11, 1959, in Santa Ana, El Salvador, William was the son of Simon Pedro Monterrosa and Rosa Maria Pleitez. He graduated from business school and received a degree in accounting from Liceo Centroamericano.
William was preceded in death by his mother, Rosa Maria Pleitez. He is survived by his father, Simon Pedro Monterrosa; and his children: William Martinez II, Mildred Luz Martinez, Walter Zaldivar, Rosemary Martinez, and Diana Martinez.
