I discovered a new character named Julio is credited on IMDb for Episodes 4 and 8 of the upcoming Season 4. Normally I would discredit this information since it's coming from IMDb, but since the role is also listed on the actor's IMDb Resume and the actor's personal Twitter feed, I think it's safe to assume it's legit.
According to his twitter feed, he was filming an episode of the Walking Dead as recent as yesterday, and has expressed an interest in appearing in more episodes this Season.
In regards to his role and character, all we can infer is that his character is some form of mechanic, based on the following tweet "I'm ready to get back on the set for The Walking Dead! Very Blessed to be on 2 episodes.LONG LIVE JULIO! The need to keep the Mechanic alive"
Now it's also entirely possible that Santiago is lying about his involvment with the Walking Dead, as some "actors" have been known to do that like Asim Ahmad and Chris Banks, who claimed to have played a Vatos in Season 1.
Sound off below on any speculation or theories on this upcoming character :D