The Equalizer S04E14 - 17 Zebra

A highly decorated NYC paramedic, Gideon (William Atherton), is on an "angel of death" killing campaign targeting homeless winos. No one suspects a thing as he drugs them and it appears they die from heart attacks. A Skid Row mission worker becomes aware that someone is doing this as his latest victim, though certified dead from a heart attack, was known to him to be in perfect health. He calls in McCall to find out who it is and stop them.