A 201 cm (6-foot, 7-inch) small forward from Duke University, Marin was named to the 1967 NBA All-Rookie Team and spent 11 seasons in the National Basketball Association (1966–1977), playing for the Baltimore Bullets, Houston Rockets, Buffalo Braves and Chicago Bulls.

[3][4] In 1966, Marin had been accepted into Duke's medical school, but decided to pursue professional basketball, and was drafted and signed by the Baltimore Bullets in 1966.

[7] Marin had an intense rivalry with New York Knicks player, and later United States Senator, Bill Bradley.

[8] Hall of Fame Knick's coach Red Holzman described them as "two intense players in a matchup of skills and the will to win.

[2][4] After retiring from the NBA, Marin entered Duke University Law School and graduated with his Juris Doctor in 1980.

[13][14] He also worked at the Raleigh firm Maupin Taylor & Ellis, where he represented NBA players as a sports agent.

In addition to being an NCAA All America player, an all ACC player, an NBA all rookie team member, and an NBA all star, Marin has been elected to the North Carolina,[4] Pennsylvania, Mercer County, Pennsylvania,[2] and Duke Athletics[3] halls of fame.