Previous Doctor (Exile)

In a parallel universe, the Doctor ran away from Gallifrey before his trial.

Early exploits
The Doctor attended the Academy with an unknown Time Lord, who found him to be "an eternal bore". Later on, he stole a TARDIS and left Gallifrey, which unintentionally annoyed the unknown Time Lord. (AUDIO: Exile)

Escaping Gallifrey
When he was about to be put on trial for breaking the non-interference policy, he escaped from Gallifrey. (AUDIO: Exile)