He Got Poisoned
Given that his execution was roughly four days away, the mission appeared to be impossible. Greg was in charge of the meals for the week; a convict is permitted to request any meal of his choosing once each week until his death. So it was the perfect way to execute his plan.
He particularly asked for a red apple because, in contrast to other hues, it would take longer for the poison to change its color. Greg gave him the poisoned apple as planned, and as soon as he ate it, everything began to happen so quickly.