Date of Birth: 1466.
Profession: Sniper.
I found this in Abstergo's database: "Gaspar de la Croix is a master weapons engineer as well as an expert marksman."
Although the profession of sniper didn't exist yet in the 16th century, Gaspar was something of a pioneer. His skill with a firearm spared him any close confrontations on the battlefield and Cesare made use of his skill to take down easy targets at the beginning of a fight.