Very little info on him can be about Kristoff anywhere, except that he was Spanish by birth, a martial artist (apparently holding a black belt in karate), ex-Foreign Legionnaire and had some legitimate training as an actor.
He appeared mostly in low-budget action and martial arts films such as Jungle Rats (1987), and Black Fire (1985), during the 80's, often directed by Teddy Page and John Gale (director).
In 1981 Kristoff was cast as a supporting player in the Richard Harrison vehicle Intrusion Cambodia, directed by John Gale.
Kristoff's most recent notable role was a small part in the Italian-Filipino Brigitte Nielsen actioner Doomsdayer (2000), directed by Michael J. Sarna and also starring former TV Tarzan actor Joe Lara and Udo Kier.
According to an interview of Nick Nicholson on the French B-movie site Nanarland, Kristoff is currently managing a restaurant in the Philippines.