The armed deputy sheriff who was on duty at the time of the Florida school shooting which left 17 students and staff members dead, never went inside the building to try and stop the gunman.
School resource officer Scot Peterson stood outside Marjory Douglas Stoneman High School, watching the western entrance of the school for more than four minutes while it suffered the attack which lasted for six minutes.
Peterson was suspended without pay and placed under investigation, but has since resigned and retired following the Valentine's Day attack.
Speaking on Thursday, Broward County Sheriff Scott Israel said Peterson should have gone into the building, "addressed the killer" and "killed the killer".
Mr Israel said the actions of his former deputy left him feeling "devastated" and "sick to my stomach. There are no words. I mean these families lost their children. I've been to the funerals. I've been to the vigils. There are no words".
President Donald Trump said the armed officer either a "coward" or "didn't react properly under pressure."
Speaking as he departed the White House for the Conservative Political Action Conference he said: "When it came time to get in there and do something" Peterson "didn't have the courage or something happened."
The suspected gunman, Nikolas Cruz, has been charged with 17 counts of murder and has admitted the attack.
Cruz's defence lawyers, state records and people who knew the 19-year-old have claimed he displayed behavioural troubles for years and was known to have had a collection of weapons.
The shooting has sparked protests and debate over America's controversial gun control laws and school safety, with gun control advocates have redoubled their efforts to get assault weapons banned.
It is thought the deadly attack was carried out with an AR-15 style assault rifle.
On Wednesday, Mr Trump met with survivors and relatives of victims of the attack, where he was told by an emotional father to "fix" the problem.
While the President largely listened during the meeting, he suggested arming teachers and promised to "do plenty of other things".
A day after the meeting, President Trump tweeted his strongest stance yet on gun control, saying he would endorse strengthening background checks, banning "bump stock" style devices and raising the minimum age to 21 for buying certain rifles.
As gun control advocates have stepped up their efforts, the influential National Rifle Association (NRA) has defended gun ownership and lashed out at Democrats calling for stricter controls - saying they are using the tragedy for "political gain."
"They hate the NRA. They hate the Second Amendment. They hate individual freedom," NRA Executive Vice President and CEO Wayne LaPierre said.