PARKLAND, Fla. -- Teachers were allowed to return to Marjory Stoneman Douglas High School Friday morning, more than a week after the deadliest school shooting in Florida's history that . Classes will resume next week.
The Florida community has grappled with recent news thatdid nothing to stop suspect Nikolas Cruz on campus, Broward County Sheriff Scott Israel said Thursday.
That failure, plus reports of a delay in security camera footage scanned by responding police and several records indicating the 19-year-old suspect displayed behavioral troubles for years, added to what the Florida House speaker described as an "abject breakdown at all levels."
CBS News correspondent Manuel Bojorquez reportsmultiple times before the Valentine's Day shooting.
According to Broward County Sheriff's Office records, they received more than 20 calls involving Cruz or his brother. Peterson was allegedly made aware of two of those calls, including one about shooting up a school and another in which a peer counselor told Peterson that Cruz ingested gasoline in an attempt to commit suicide.
Peterson took up a position viewing the western entrance of Building 12 for more than four minutes after the shooting started, but "he never went in," Israel said.
The shooting lasted about six minutes.
Peterson was subsequently suspended without pay and placed under investigation. He later chose to resign from the department.
Asked what Peterson should have done differently, Israel said the deputy should have "went in, addressed the killer, killed the killer."
Cruz has been jailed on 17 counts of murder and has admitted to carrying out the attack. He owned a collection of weapons. Defense attorneys, state records and people who knew him have described troubling incidents going back years.
Broward County incident reports show that unidentified callers contacted authorities with concerns about Cruz in February 2016 and November 2017. The first caller said they had third-hand information that Cruz planned to shoot up the school. The information was forwarded to Peterson. The second caller said Cruz was collecting guns and knives and believed "he could be a school shooter in the making."
Also in November 2017, Cruz was involved in a fight with the adult son of a woman he was staying with shortly after his mother died, according to a Palm Beach County Sheriff's Office report. On Nov. 28, a 22-year-old man at the Lake Worth home told the responding deputy the he tried to calm down Cruz, who had been punching holes in walls and breaking objects, but Cruz hit him in the jaw, and the man hit Cruz back.
The deputy found Cruz a short time later at a nearby park. Cruz told the deputy he had been angry because he misplaced a photo of his recently deceased mother, and he apologized for losing his temper.
The other man told the deputy he didn't want Cruz arrested. He just wanted Cruz to calm down before coming home.
CBS News has also learned there was a 20 minute delay in the school's surveillance video. Police say that caused confusion for officers during the shooting trying to find the gunman, but police say no more lives were put in danger because of it.
That failure is one of many admitted missteps by local and federal law enforcement.
The FBI is dealing with its handling of complaints made against Cruz. A federal law enforcement source describes the failure on the FBI's end as a "body blow" for the entire bureau.
The shooting has reignited national debate over gun laws and school safety, including proposals by President Trump and others to designate more people -- including teachers -- to carry arms on school grounds. Gun-control advocates, meanwhile, have redoubled calls for bans or further restrictions on assault rifles.
Politicians under pressure to tighten gun laws in response to the mass shooting floated various plans Thursday, but most fell short of reforms demanded by student activists who converged Wednesday on Florida's Capitol.
Florida House Speaker Richard Corcoran said Thursday night that his chamber is going to recommend creating a special commission to investigate the "abject breakdown at all levels" that led to the shooting deaths. The Republican said the commission, likely be led by a parent of one of the slain children, would have subpoena power.
Corcoran said the news about the resource officer's failure to respond did not dissuade him from moving ahead with what he was calling the "marshal" plan to let local law-enforcement officials train and deputize someone at the school who would be authorized to carry a gun.
State Sen. Bill Galvano, who is helping craft a bill in response to the shooting deaths, insisted the idea is not the same as arming teachers. He said the program would be optional and the deputized person would have to be trained by local law-enforcement agencies.
U.S. Sen. Marco Rubio of Florida said a visit to Stoneman Douglas prompted him to change his stance on large capacity magazines. The Republican insisted he is willing to rethink his past opposition on gun proposals if there is information the policies would prevent mass shootings.
On Friday morning, Florida Gov. Rick Scott is expected to announce his plan to improve school safety and outline ways to keep guns away from those with mental illness.