Experts said Tuesday the alleged shooter in the massacre may have difficulty making the case for a successful insanity plea.
Paul Callan, a criminal defense attorney and a former prosecutor, and Jeff Gardere, a clinical and forensic psychologist, told CNN's "American Morning" on Tuesday they have doubts that an insanity plea would stand.
With the "amount of planning that went into this assassination," Callan believes "it's highly unlikely he will meet the legal insanity defense threshold."
"It's very hard to prove insanity at trial," Callan said. "You really have to prove that your mental illness is so severe that you don't even understand that you're committing a criminal act. And it's almost impossible to prove that."
Gardere emphasized that "premeditation will work against him in this one as far as getting an insanity plea."