A stumbling Framingham SWAT officer accidentally fired his rifle and shot a beloved grandpa to death as he lay face-down on the floor of his own home, authorities admitted yesterday, sparking incredulous outrage by the 68-year-old retiree’s family.

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Officer Paul Duncan, who fired the fatal shot, did so after he tripped during a search of Stamps’ home, according to a report issued yesterday by Middlesex District Attorney Gerard Leone’s office. Duncan will not face charges.

“The actions of Officer Duncan do not rise to the level of criminal conduct, and the shooting death of Eurie Stamps was an accident,” Leone’s office said.

On Jan. 5, police were searching for Stamps’ stepson, Joseph Bushfan, when they served a warrant on Stamps’ home. Bushfan was arrested outside the home, allegedly carrying crack cocaine and money.

Officers then hit the home, throwing a stun grenade and ordering everyone inside to put their hands up and lie on the floor, the report states. Stamps, a grandfather of 12, had obeyed and was lying in the hallway when Duncan attempted to cuff and frisk him.

“As he stepped to his left, (Duncan) lost his balance and began to fall over backwards,” the report states. “Officer Duncan realized that his right foot was off the floor and the tactical equipment that he was wearing was making his movements very awkward. While falling, Officer Duncan removed his left hand from his rifle, which was pointing down towards the ground and put his left arm out to try and catch himself. As he did so, he heard a shot.” (...)