Updated

The Florida deputy who resigned after it emerged he didn't enter Marjory Stoneman Douglas High School during the mass shooting on Valentine's Day is not "a coward" and acted appropriately, his lawyer said in a statement Monday.

Broward Deputy Scot Peterson has been heavily criticized for failing to enter the school and confront the gunman, 19-year-old Nikolas Cruz, during the rampage that left 17 people dead.

Peterson had been assigned to guard the school, and his actions -- or lack of them -- were even lambasted by President Trump, who called Peterson "a coward" last week. Trump on Monday again slammed Peterson and other officers who allegedly did not enter the school, saying "the way they performed was frankly disgusting."

Peterson's lawyer Joseph DiRuzzo said in a news release obtained by Fox News the one-time school resource officer of the year didn't go inside the high school because he believed the shooting was happening outside the building.

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Deputy Scot Peterson, shown speaking in 2015, was armed and stationed on campus when Nikolas Cruz opened fire.

"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," according to the statement. "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."

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DiRuzzo said Peterson is confident he followed procedures and will be exonerated.

Peterson contends he took up a position outside Building 12 at the school after rushing over to respond to a report of firecrackers, "and not gunfire."

"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."

— Joseph DiRuzzo, Scot Peterson’s lawyer

Once he got to the building, Peterson said he “heard gunshots but believed that those gunshots were originating from outside of any of the buildings on the school campus."

“BSO trains its officers that in the event of outdoor gunfire one is to seek cover and assess the situation in order to communicate what one observes with other law enforcement," the statement said.

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Florida Gov. Rick Scott, right, said the police response to the Parkland high school shooting will be investigated. Dozens of lawmakers are demanding Scott suspend Israel (AP)

He said he was the first Broward deputy to dispatch on police radio shots were being fired, and he told a first-arriving Coral Springs officer he “thought that the shots were coming from outside.” That arriving officer then took up a tactical position behind a tree with his rifle.

“Radio transmissions indicated that there were a gunshot victim in the area of the football field, which served to confirm Mr. Peterson’s belief that the shooter, or shooters, were outside,” according to the statement.

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He also said he “had the presence of mind” to have school officials review cameras at the facility “to locate the shooter" and obtain a description for law enforcement.

Peterson resigned last week after Broward County Sheriff Scott Israel accused him of failing to confront the shooter.

His lawyer blasted Israel for his criticism of the officer, adding that judgment should be withheld until the investigation into the school shooting is complete.

"It is our understanding that Sheriff Israel acknowledged that the investigation remains on-going and that '[i]nvestigations will not be rushed or asked to jump to conclusions.'  But this is exactly what Sheriff Israel did, he jumped to a conclusion regarding Mr. Peterson’s performance on February 14th even though Israel claims that '[i]t is more important for us to wait and let the investigators get it right[.]' We question why this statement would not also apply to Mr. Peterson?" the statement said.

Some politicians have said Israel needs to step down because his office ignored repeated warnings about Cruz.

On Sunday in an interview with CNN, Israel slammed a letter from State Rep. Bill Hager to Florida Gov. Scott, which called for his removal on the basis of inaction after at least 23 -- and perhaps almost 50 -- police visits to the shooter’s home and the reports of his officers standing idle.

Israel said the demand was a “shameful, politically motivated letter that had no facts.”

Fox News'  Greg Norman, and The Associated Press contributed to this report.