He moved to the United States in 1948 and became a protege of Eero Saarinen, the Finnish American architect. He was Saarinen's principal design associate for several years. After Saarinen's death in 1961, Roche and colleague John Dinkeloo supervised the completion of their mentor's unfinished work, including Dulles International Airport, the Gateway Arch in St. Louis, and the T.W.A. terminal at Kennedy International Airport in New York.