The Broward County Sheriff's Office released the video on Thursday showing disgraced former Deputy Scot Peterson's actions during the February 14 shooting at Marjory Stoneman Douglas High School in Parkland.
In the days following the massacre, Broward County Sheriff Scott Israel said Peterson should have gone into the building and "killed the killer".
New surveillance footage has been released of the Valentine's Day school shooting in Parkland, Florida, in which 17 people were killed.
The Broward County Sheriff's Office on Thursday released 30 minutes of surveillance video taken outside the high school following a judge's order, citing "strong public interest".
Broward County Sheriff Scott Israel speaks before the start of a CNN town hall meeting in Sunrise, Florida, Feb. 21, 2018. "After being suspended without pay, Peterson chose to resign and immediately retired rather than face possible termination", the department said in a brief statement with the video's release.
That contradicts a statement issued February 26 by his lawyer saying Peterson, who was assigned to the school, "believed that those gunshots were originating from outside any of the buildings on the school campus".
A final shot, which lasts roughly 26 minutes, shows what police say is Mr Peterson outside of the building - at least for a portion of the clip - while pixelated students file past him.
The bulk of the 27-minute video released by authorities is of an empty sidewalk at the school.
Peterson's radio calls in the minutes after shooting show he nearly immediately realised gunshots were being fired inside Marjory Stoneman Douglas High School. A state panel approved by lawmakers is also going to review the law enforcement response to the shooting and prior contacts that officials had with the suspected gunman, who had repeatedly come to the attention of police and the Federal Bureau of Investigation before the massacre. Sheriff Scott Israel, who has been another lighting rod for controversy for saying he's exhibited fantastic leadership, commented that he was sick to his stomach when he saw the footage of his deputy not entering the building.
The clips only show the police response outside, not the horror that occurred within.
Watch the full unedited footage above, via the Broward Sheriff's Office.
At 2:23 Peterson arrives at the building where the shooting was taking place and takes a position outside.
On Wednesday, Cruz was arraigned on 17 counts of premeditated murder in the first-degree and 17 counts of attempted murder in the first-degree.
His attorney, Assistant Public Defender Melisa McNeill, reiterated that Cruz would plead guilty if prosecutors waived the death penalty, which they refused to do.
But that mishap "never put us in a situation where any kids' lives were in danger, any teachers' lives were in danger", said Coral Springs police Chief Tony Pustizzi, whose officers responded to the scene.