"Obviously there's issues of sanity and competency, says criminal defense lawyer Lawrence Hashish. "First to see if this defendant is competent to stand trial."
When and if that's determined, Hashish says, the next place to look would be Alaska. In November last year Santiago went to the FBI field office in Anchorage claiming he was hearing voices – that the government was controlling his mind and forcing him to watch ISIS videos.
"It would lay the possible insanity defense in the future, if it is to be used. But clearly there's signs of it," Hashish says.
After spending a handful of days with doctors, they released the Iraq war veteran and eventually gave him his handgun back.
Hashish said overall it would be long shot considering the evidence against him.
"It's a very big uphill battle. It's on camera, 100's of witnesses and confession."
And for the prosecution:
"As a prosecutor, I'm going to want access to his mental health evaluations," David Weinstein, a formal federal prosecutor says. He is now a partner at the Miami-based law firm Clark Silverglate.
The evaluation he would want most: The Alaskan doctors that cleared Esteban Santiago and gave him his gun back after he told the FBI he was hearing voices in his head-claiming the government was telling him to watch ISIS videos.
"I want to see what the diagnosis was at the time they discharged him," he says. "There wasn't enough evidence for a doctor to conclude that he was incompetent and that he should be committed."
But there's still the unanswered question as to what triggered Friday's attack.
What happened to the 26-year-old between meeting with the FBI in Alaska, to coming to Fort Lauderdale?
"That was in November. We're in January already. I don't know. None of us know what it was that caused him to fall into that state," he says. "So he needs to be evaluated again."
He says there's a good chance this case can be tried by the end of this year and for it to proceed as a death penalty case.
Santiago will appear in court next week to determine if he should be released on bond, although that's unlikely.