Martinez was born in 1941 in Santo Domingo, Dominican Republic.
Martinez served in the United States Naval Reserve from 1964 to 1993, and was a Navy legal officer from 1965 to 1968.
He was an assistant United States attorney for the Southern District of Florida from 1968 to 1970.
From 1972 to 1974, he was regional director of the Office for Drug Abuse Law Enforcement of the Department of Justice.
President George W. Bush nominated Martinez to the United States District Court for the Southern District of Florida on January 23, 2002, to the seat vacated by Judge Edward B. Davis.