(MCT) — Now that a defense attorney for Colorado shooting suspect James E. Holmes has referred in court to his client’s unspecified “mental illness,” it is a near certainty that the trial of the 24-year-old former doctoral student will turn on his mental state, legal experts said.

A desire to understand the motive behind the rampage that left 12 dead and 58 injured in a suburban Aurora movie theater has fed speculation about the inner logic of the accused. Was Holmes an angry depressive out to seek revenge, with knowledge of right and wrong? Was he suffering a psychotic break caused by the onset of schizophrenia or some similar illness?