When police arrived at Marjorie Stoneman Douglas High School on 14, February, 2018 — as gunshots continued to echo through its halls — they made a shocking discovery.
On the east side of the building, his gun drawn as though holding the entire facility at bay, stood Broward County Sheriff's Deputy Scot Peterson. A police officer from the Sunrise Police Department came across Mr Peterson on his way to the school, and found him repeating the phrase "Oh my God, I can't believe this."
Mr Peterson was the first person to radio in reports of a mass shooting at the school, but he was not the first to engage with shooter Nikolas Cruz. Instead, he fled the building, and advised other police to do the same, as the gunman murdered 17 people inside.
The now-former deputy — relieved from duty following the shooting — has maintained he followed police protocol and was not a coward.
Now, more than five years since the mass shooting, Mr Peterson will have to make that case to a jury.
Mr Peterson, now 60, faces 11 charges, including seven counts of felony child neglect, three counts of culpable negligence, and one count of perjury in connection with the shooting and related statements.
If convicted, he could spend more than 100 years behind bars.
He has pleaded not guilty to all charges.
The day of the shooting
Shortly after the shooting began, Mr Peterson called in a report to local police that gunfire had broken out near the school. He was outside the school at the time of the attack, but rather than rushing in to confront the gunman, he stayed outside, approximately 75 feet away.
He remained outside for 45 minutes, well after local police arrived to respond to Cruz, according to VICE.
The Florida Department of Law Enforcement investigated Mr Peterson's actions on the day of the shooting, and collected statements from witnesses and footage from video cameras at the property to determine whether or not the deputy's actions were congruent with his training and obligation.
A student witness who spotted Mr Peterson said he was "standing on the side of the building with his gun drawn, not really doing anything."
Another student told investigators that they spotted the deputy in a kevlar vest, but that he appeared to be doing very little beyond pointing his gun at the building.
Peterson's version of events
Mr Peterson told the Parkland Public Safety Commission investigating the shooting that he was not cowering, but was "taking a position on the east side of the [school's] doorway."
He described the decision as one borne of tactics, not terror, claiming staying outside allowed him to "see down the sidewalk looking out west."
"I get a good two dimensional ... of that whole building at that point," he told the commission.
Since the shooting, Mr Peterson has maintained that he followed his training for an active shooter situation by setting up a perimeter outside the school and calling in a Code Red to trigger a lockdown.
“Let there be no mistake, Mr. Peterson wishes that he could have prevented the untimely passing of the seventeen victims on that day, and his heart goes out to the families of the victims in their time of need,” his attorney, Joeseph DiRuzzo III, said in a statement in 2018. "However, the allegations that Mr. Peterson was a coward and that his performance, under the circumstances, failed to meet the standards of police officers are patently untrue."
Mr Peterson has maintained that he did not know where the shooting was coming from, and remained outside as he believed the shooting may have originated at the school's football field.
Investigators have presented evidence they say conflicts with Mr Peterson's account of his activities the day of the shooting.
Dispatch calls from the day of the shooting suggest that Mr Peterson believed that the shots were occurring near the 1200 block of the school building. That was an accurate assessment, as that's where Cruz was carrying out the attack.
Other officers who spoke with Mr Peterson on the day of the shooting told investigators he had advised them the gunman was inside the 1200 block – not just near it
Investigators have also noted that, contrary to Mr Peterson's training claims, the standard policy for police responses to active shooters it to engage them, not to fall back.
Rick Swearingen, the commissioner of Florida Department of Law Enforcement, said the investigation's findings showed Mr Peterson did "absolutely nothing" to stop the attack.
“The investigation shows former Deputy Peterson did absolutely nothing to mitigate the MSD shooting that killed 17 children, teachers, and staff and injured 17 others,” he said after the agency reported its findings. “There can be no excuse for his complete inaction and no question that his inaction cost lives.”
After the shooting
When Mr Peterson's actions were reported to the public, an already furious nation turned against the deputy for his alleged inaction.
At the time, then-President Donald Trump called him a "coward" who "didn't have the courage" to confront Cruz.
Fred Guttenberg, who became a gun-control activist after his daughter was killed in the attack, offered his unfiltered opinion in a tweet after the incident.
“I have no comment except to say rot in hell,” he wrote. “You could have saved some of the 17. You could have saved my daughter. You did not and then you lied about it and you deserve the misery coming your way.”
Mr Peterson was eventually suspended and later resigned.
Following a 15-month investigation into his alleged inaction, prosecutors brought 11 charges against him and took him into custody.
His bond was set at $102,000, and he was required to wear a GPS tacker and surrender his weapons.
“I know at the end of the day I have to believe in justice, because I didn’t do anything wrong that day at all,” Mr Peterson told Men's Health. “I sleep at night because I know that. So I believe in the rule of law; I believe in justice. I believe when the facts of what occurred actually come out ... The families that lost their kids, they’ve never been told the truth of what happened at that shooting.”
After more than five years, Mr Peterson will have to test his actions during the shooting against the prosecution's evidence that he was negligent.
Leading up to the trial, Mr Peterson's lawyers asked a judge if the jury could visit the spot where the former deputy was standing during the shooting, CNN reports.
The prosecution agreed, but wanted to add an additional stop to the jury's fieldtrip; they wanted the jurors to walk the halls of the high school.
The defence was extremely opposed to the idea. The judge ultimately ruled there would be no travel at all.
“While we are disappointed that jurors won’t be able to visit the school to see the area around the 1200 building, we are extremely grateful that the judge didn’t permit the State to walk them through the inside of the building as that would have no relevance to the issues in dispute and only serve to traumatize jurors by exposing them to the dried blood of injured and dead children,” Mr Peterson’s attorney said in a statement reported by WPLG.
The jurors were selected on Wednesday, consisting of four women and two men.