Former Broward County Sheriff's Deputy Scot Peterson has been arrested and charged in connection with his failure to try to stop the massacre at Marjory Stoneman Douglas High School in Parkland, Florida.

What's the background?

On Feb. 14, 2018, 14 students and three adults were murdered at Marjory Stoneman Douglas High School, and 16 others were injured. While the attack was ongoing, Peterson, then a school resource officer, was on campus. He chose to take cover instead of trying to confront the attacker, a disgruntled former student. He also ordered other police officers to stay back away from the building.

Peterson would later defend his actions, telling NBC News in June 2018 that he was "sorry" about what happened but that he had been "trying to do the best I could with no information or intel at the time...and it was just happening so fast."

But evidence released later that same year, including audio from Peterson's police radio, and a video that tracked the relative positions of both Peterson and the shooter, painted a different story. At a Stoneman Douglas High School Public Safety Commission meeting in September, commission chairman and Pinellas County Sheriff Bob Gualtieri said that this proved that Peterson not only made no effort to help, but also slowed the response of other law enforcement units.

What happened now?

The Florida Department of Law Enforcement announced in a news release on Tuesday that Peterson had been arrested and charged with seven counts of neglect of a child, three counts of culpable negligence, and one count of perjury. All counts were related to the Parkland massacre.

In a statement, FDLE commissioner Rick Swearingen said "[t]he FDLE 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 added "[t]here can be no excuse for his complete inaction and no question that his inaction cost lives."

The FDLE said that Peterson's case would be handled by Assistant State Attorney Tim Donnelly.