(CNN) The armed resource officer for Marjory Stoneman Douglas High School who didn't enter the building where an active shooting was taking place said through his attorney that he thought the shots were coming from outside. But in dispatch audio of the incident, he said he had heard that it was "by, inside the 1200 building."

The discrepancy was revealed in an updated timeline and dispatch audio of the Florida school shooting released Thursday by the Broward County Sheriff's office.

Broward County Deputy Scot Peterson, who worked as the school's resource officer, was publicly shamed by Sheriff Scott Israel and President Donald Trump in the aftermath of the February 14 massacre that left 17 students and teachers dead.

Israel told reporters that when he saw video of Peterson staying outside Building 1200 and never going in, it made him "sick to his stomach." Trump said Peterson "did a poor job" because he "didn't have the courage" to do what he was trained to do.

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Peterson initially defended himself in a statement through his attorney by saying he'd received a call about "firecrackers" and that he didn't enter the building because he "believed those gunshots were originating from outside of any of the buildings on the school campus."

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