"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,'" Cruz's attorney Howard Finkelstein told ABC News. "I don't know what you can do more than that to get somebody's attention."
Among the growing list of warning signs either detailed by public statements from officials or public records are:
-- Investigators dissecting Cruz's social media accounts since the mass shooting have found posts that Broward County Sheriff Scott Israel described to ABC News as "very, very disturbing."
-- Broward County School District officials saying Cruz was reprimanded regularly while a student at Marjory Stoneman Douglas High School and eventually expelled. Jim Gard, a math teacher at the school, told ABC News he believes Cruz had been banned from bringing a backpack to school when he was a student there.
-- At least 20 calls for service in the last few years regarding Cruz for a variety of disturbance complaints, including fighting with his mother, who died in November after contracting pneumonia, authorities said. In a police report from Sept. 28, 2016, a therapist who went on one of the calls cleared Cruz, concluding he was “no threat to anyone or himself.”
-- One of Cruz's classmates told ABC News that about a year ago, Cruz told him, "I swear to God I'll shoot up this school." But the student did not report the threat to school officials after Cruz apologized for making it, the student said.
During a gun control rally in Fort Lauderdale on Saturday, Emma Gonzalez, a student at Stoneman Douglas, told a crowd that students had reported Cruz numerous times for his behavior.
"We did, time and time again since he was in middle school," Emma said. "It was no surprise to anyone who knew him to hear he was the shooter."
Robert Runcie, the Broward County School District superintendent, declined to comment on Cruz specifically, but told ABC News in an interview on Sunday, that the district follows up on all complaints about students.
"They are disciplined, they are reviewed," Runcie said. "In schools, we provide counseling and support to the greatest extent possible.
"But there are limitations for what we can do at a legal standpoint right now," Runcie said. "If a student has serious issues, we collaborate when appropriate with law enforcement agencies on when to take action. But the big challenge, I believe, is that we have various agencies, including the school system, that are working really hard but in silos."
Runcie said there isn't a system available in which the schools, law enforcement, social service agencies and mental health agencies share information that could possibly connect the dots about a particular student.
"We're gonna certainly review this and all of us in our respective areas are gonna figure out how we can improve on what we are doing," Runcie said. "But at the end of the day, there's got to be legislation, there has to be some type of infrastructure built so that we're all working smarter instead of just harder in our own silos, if you will."
Israel told ABC News that he's ordered an investigation into all 20 calls regarding Cruz to "look at what our deputies did, and if our deputies acted inappropriately, or missed and didn't do what our leaders think they should've done."
But Israel said his deputies often find their "hands are tied" by laws. He said the state's Baker Act -- which gives law enforcement the ability to involuntarily take someone suffering from mental illness to a facility to be examined if they are an immediate threat to themselves or others -- needs to be expanded.
"We have to be able to when we read disturbing texts, when somebody says 'I want to be a school killer' ... we need the ability to involuntarily Baker Act someone for what we think they might do," Israel said. "That has to be done in this day and age."
But Israel said nothing will change unless Congress acts to strengthen gun laws to keep weapons out of the hands of people with a history of mental illness.
"They deserve and we deserve to have them confined, and when they're examined and somebody says they're ready to be released, they should be released and they shouldn't be able to come over with an order and have us give them their handguns," Israel said.
"They're not better three or seven days later," he said. "They're not better, they're not healed. We don't know what's gonna happen. We need to keep their guns."