In a press conference Thursday, Israel said the armed deputy, Scott Peterson, was on campus during the shooting but failed to go inside to engage the accused shooter, Nikolas Cruz.
The decision to suspend Peterson was made after witness statements, video and Peterson's own statement, Israel said.
"What I saw was a deputy arrive at the west side of Building 12, take a position and he never went in," Israel added.
Instead of facing the suspension, Peterson decided to resign/retire.
Cruz is accused of killing 17 people in the nation's deadliest school shooting since a gunman attacked an elementary school in Newtown, Connecticut.
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