Indiana Jones encountered Dr. Victor Van Loon while exploring Site R in the 1930's. He was a shady private collector and treasure hunter, pretending to be a real archeologist.
On several occasions, Indiana Jones had to intervene and stop Van Loon from stealing precious artifacts, such as the Toltec Crystal Skull, the Eagle Dagger, and the Coatlicue Idol.
He once kidnapped local tribal leader Pacal Hunac in order to coerce Jones to reveal the location of a secret tomb, rumored to contain fabulous treasure. Jones tricked Van Loon by giving him a very convincing fake map and thus released Hunac.