Cruz was the physician at the modern Clínica Santa María hospital at Puntarenas. He had his education in the USA.

In the The Lost World he treated Tina Bowman's wounds and allergic reaction from her encounter with a Procompsognathus. He found the reaction very strange, therefore called his friend Martin "Marty" Guitierrez (who is a biologist from Yale working in Costa Rica) for advice.

Every morning he wears a clean shirt, but not a new tie.