US-NEWS-MAINE-SHOOTING-MCT

This photo released by the Lewiston Maine Police Department shows Robert Card, whom police found dead after his shooting rampage that left 18 dead in Lewiston, Maine, on Oct. 25, 2023. (Lewiston Maine Police Department/TNS)

Maine's medical examiner has sent part of Lewiston mass shooter Robert Card's brain to a lab in Boston to look for signs of injury — possibly connected to his military service — that could have played a role in his sudden and violent shift in behavior.

Lindsey Chasteen, a spokeswoman for the Office of Chief Medical Examiner, said Monday that brain tissue from Card has been sent to Boston University, which has the nation's largest brain bank focused on studying chronic traumatic encephalopathy, or CTE.