The office of New York’s attorney general released body camera footage Friday showing the fatal beating of a state prisoner this month by correctional officers who punched and kicked him repeatedly while he was handcuffed on an infirmary bed.

The incident, which has drawn outrage from political leaders and was condemned by the officers’ union as “incomprehensible,” is being investigated by state Attorney General Letitia James. The inmate, Robert Brooks, 43, died in the hospital a day…