In 1499, Garza and his ally Ubayd Alayza hunted Assassin sympathizers in the city of Granada and turned them over to the Spanish Inquisition. Though the Spanish Assassins tracked him down to his villa, hoping that he would lead them to Ubayd's location, he escaped to the Alhambra. 
In the Alhambra fortress, Garza and Ubayd argued about their actions, with his charge doubting the Templars' methods, before Garza drew his knife and violently stabbed Ubayd in the gut three times before fleeing the garden and leaving Ubayd to bleed to death.
Graza fled through the streets of Granada, with the Spanish Assassins and their ally, Najma Alayza, hot on his heels. The Assassins made their way through the towers and along the walls, eventually cornering Garza on the edge of a rampart. Najma then assassinated Garza with her Hidden Blade.