Authorities have sent part of the brain of Robert Card, the former Army reservist who died of a self-inflicted gunshot wound in October after carrying out a devastating shooting spree in Lewiston, Maine, to a lab in the hopes that it will shine a light on how his mental state rapidly unwound. Specifically, authorities are investigating whether Card’s repeated exposure to explosions as an Army grenade instructor may have caused an unseen traumatic injury and contributed to his decline, according to The New York Times. This may include chronic traumatic encephalopathy, known as C.T.E, a condition commonly associated with contact sports athletes which can only be diagnosed after a patient has died.