Early life

Marshall was born in Pittsburgh, Pennsylvania. He later lived in Georgia, then moved to Florida, where he played high school football at Lake Howell High School. Marshall played both offense and defense, as he earned All-State honors and was named Seminole County Utility Player of the Year. He also lettered in basketball and track three times. As a senior, Marshall won the Class 3A state triple jump championship, landing a jump of 48-feet, six-and-three-quarter inches.

College

Marshall played a total of 44 games (21 starts) at wide receiver for the University of Central Florida, collecting 112 receptions, 1,674 receiving yards and 13 touchdowns in his collegiate career. His best season came in 2005 as a senior. He played in 13 games and had career highs in receptions (74), receiving yards (1,195) and touchdowns (11). Marshall's best career game came in the 2005 Hawaii Bowl, where he had 11 catches for 210 yards and three touchdowns. He was named MVP of the game. For his efforts during the 2005 season, Marshall was selected to the All-C-USA second team.

Marshall also started at safety for seven games during the 2004 season due to injuries in UCF's secondary. He made his first collegiate start at safety on October 4, 2004, against Buffalo. He recorded four tackles, including a half of a sack. Marshall led his entire team in tackles (51) during the 2004 season. He also had an interception and a forced fumble.