Confessed Florida school shooter Nikolas Cruz had a history of violence inside the walls of Marjory Stoneman Douglas High School prior to his attack on Wednesday.
Video obtained by ABC's Local 10 News shows the former Parkland, Florida, student fighting with classmates at his former school on September 20, 2016.
Cruz was suspended for two days following the incident, which was one of five times officials at the school disciplined him while he was a student there. In February 2017, he was transferred to another school following a separate rule-breaking incident.
"Every day we're learning something more and more about the killer," Broward County Sheriff Scott Isreal said of Cruz, who confessed to opening gunfire with his AR-15 rifle on Wednesday, killing 17 people.
Over the last few years, the Broward Sheriff's Office received more than 20 calls about Cruz while he was living with his adopted mother and, after her death in November, with a family friend. He later moved in with another family around Thanksgiving, who claim Cruz caused no trouble in their home.
"The police were in the driveway a lot," one former neighbor said of Cruz's residence. Others said they contacted the authorities about Cruz, but their warnings were not investigated.
"This kid, in his own way, was screaming out in every way the mind knows how to scream out. He did everything including saying, 'I want to go and shoot people in school.' I don't know what you can do more than that to get somebody's attention," said Howard Finkelstein, Cruz's court-appointed lawyer, Local 10 reports.
The FBI also received a tip on January 5 warning them about Cruz, citing details about his guns and desire to kill people, erratic behavior and disturbing social media posts. Cruz had reportedly been bragging about killing small animals and sharing his plans to shoot people while conversing on a private chat group.
As a potential threat to life, the tip should have been forwarded to the FBI's Miami field office for investigation, but that never happened.
"The potential of the FBI to miss something is always there. We do our best. [We're] looking where or how protocol broke down," Robert Lasky, the special agent in charge of the FBI's Miami field office, said in a statement.
On February 14, Cruz entered his former high school and triggered the fire alarms ahead of afternoon dismissal. As students herded into the hallways to exit Building 12 of the school, he sprayed bullets upon innocent students and staff, killing 17 people and injuring several others.
He is being held at Broward County Jail without bond and is expected to plead guilty to 17 counts of premeditated murder.