A neuro-psychologist hired by the defense suspects Michael Hernandez, 14, may have a brain abnormality that causes violent impulses, The Miami Herald reported Friday.
If that turns out to be the case, attorney Richard Rosenbaum said it could lead to a defense of insanity.
Hernandez already has received a PET scan but results of most of the tests won't be ready until next month.
Miami Circuit Judge Henry Leyte-Vidal has ruled Hernandez is competent to stand trial as an adult.
He is charged with first-degree murder in the slaying of 14-year-old Jaime Gough, who was stabbed to death in February in a restroom at Southwood Middle School.
Hernandez's trial date has been set for May 9.