After his military training, which belonged to the tradition of his family, he moved to Los Angeles and his acting career began. He played numerous roles in different popular series, such as One Life to Live and Beverly Hills, 90210. His breakthrough role, however, was the one of Johnny Rico in the 1997 cult movie Starship Troopers by Paul Verhoeven. Playing that part led to him being cast in a lot of productions, the first one being Tarzan and the Lost City, where he played none other than Tarzan himself! In 1997, he was cast for the role of Brom von Brunt in Tim Burton's Sleepy Hollow along with Johnny Depp. His most prominent role, Johnny Rico, recurred in the sequel Starship Troppers 3: Marauder and Casper was again asked to play him. At the moment he is filming Aaah! Roach! and his next project will be Garrison 7: The Fallen alongside Mark Dacascos.