Marshall earned All-WPIAL and All-Big Ten honors at Clairton High School. He went to Potomac State Junior College, where he was selected as an honorable mention junior college All-American and was the leading tackler on the squad. In January 1974, Marshall transferred from Potomac State Junior College to WVU. He was listed as the number two middle linebacker. While on the WVU football team, he played behind Steve Dunlap in nine games; he had 71 tackles and three quarterback sacks in those games. He majored in political science with hopes of going to law school.