Letterlough became a professional boxer in 1998 at the late age of 28 after a seven-year stint in prison for assault. He fought as a
light heavyweight and was unbeaten in his first 16 fights. He fought against
Julio César González in 2001, a fight in which González was down three times, and Letterlough down twice. González won by decision. Later that year, he got a shot at
International Boxing Federation cruiserweight titleholder
Vassiliy Jirov, but lost in the 8th round by TKO. He lost a decision later that year to David Telesco, and in 2003 was knocked out by
Richard Hall. In 2004 he fought a draw against
Daniel Judah, a fight in which Judah went down in round five and was docked a point for holding in round seven. ==Professional boxing record==