Graduated from New York's American Academy of Dramatic Arts in 1983,
along with (among many others) actors
Elias Koteas,
Illeana Douglas,
Louis Mustillo,
Adam Klugman,
Jody Wood,
Elisa Anders,
Jonathan Mandell, and
Michael Reid Carter. After graduating,
Markinson, Koteas, Wood, Anders, Mandell, and Carter were members of the
Academy of Dramatic Arts' 1983-1984 Production Company.