US athlete Jim Thorpe won two gold medals at the 1912 Olympics, but why were they taken away in 1913?

Axel, dang shame.

This from ESPN: During the summers of 1909 and 1910, Thorpe was paid - reports have him earning from $2 a game to $35 a week - for playing for Rocky Mountain in Fayetteville in the Class D Eastern Carolina League. He naively used his real name, unlike other collegians who adopted pseudonyms to foil amateur rules. Then again, Thorpe may have thought he would never compete as an amateur again. It took some arm-twisting by coach Pop Warner to get Thorpe to come back to Carlisle for the 1911 football season. Warner promoted Thorpe as "the greatest all-around athlete in the world."