Alleged Florida school shooter Nikolas Cruz was reported to FBI, cops, school -- but warning signs m

Nikolas Cruz, the 19-year-old accused of killing 17 people at his former Florida high school, had scores of run-ins with law enforcement dating back to 2010 -- with one report saying sheriff’s deputies responded to his home more than 35 times in just six years.

Broward County Sheriff’s deputies received at least 36 emergency 911 calls from 80th Terrace St., in Parkland – the suburban address where the teenager lived with his younger brother, Zachary, and their adoptive mother, Lynda, BuzzFeed reported.

The calls – dating as far back as 2010 and continuing until November 2016 – shed a light on two erratic and violent boys who repeatedly “threw items,” were “out of control” and fought with their mother and each other on an apparently regular basis.

NIKOLAS CRUZ WAS LIVING WITH HS STUDENT IN MONTHS LEADING UP TO MASSACRE, ATTORNEY SAYS

Despite the repeated calls to authorities, Cruz was never arrested – and was basically cleared as being “no threat to anyone or himself,” as one therapist said in a police report from Sept. 28, 2016.

In that particular call, the sheriff’s office said Nikolas and his mother were fighting over paperwork needed for him to get an ID card

In their report, deputies detailed how the teen had been harming himself and had talked about buying a gun.

“He had been cutting his arms, his mother said, to get attention, as he learned it from an ex-girlfriend,” deputies said. “He has mentioned in the past that he would like to purchase a firearm.”

The therapist on scene, Jared Bienenfeld with Henderson Mental Health, and the deputies concluded there were “no signs of mental illness or criminal activity.”

And much like the calls before – which were placed due to reasons ranging from the brothers beating each other to Cruz, at the age of 12, threating his mother and calling her a “useless b****” – law enforcement left without taking any further action.

A public information officer with the sheriff’s office could not verify the report to Fox News early Friday morning. The sheriff’s office did not immediately respond to additional requests for comment.

Cruz was never arrested until this Valentine’s Day when he allegedly walked into Marjory Stoneman Douglas High School with a gas mask, smoke grenades and multiple magazines of ammunition before firing an AR-15 at students and faculty members.

He was charged with 17 counts of premeditated murder on Thursday and is being held without bail.

In the aftermath of the attack, revelations about the teen's alarming warning signs appeared to be repeatedly missed -- despite the cop calls, a report to the FBI based on a social media posting, his former classmates expressing fear of him and a documented history of mental health issues.

TRUMP: 'SO MANY SIGNS' FLORIDA SHOOTING SUSPECT WAS 'MENTALLY DISTURBED'

"I think everyone had in their minds if anybody was going to do it, it was going to be him," Victoria Olvera, a 17-year-old junior at the school, told the Sun-Sentinel.

According to reports, Cruz and his brother both suffered from mental health issues, including ADHD and OSC, and took medication as treatment. Cruz's lawyer said Thursday her client was "a broken human being" and the team was looking into an evaluation for autism. Nikolas had sought treatment at Henderson mental Health Clinic and had previously attended a school for students with behavioral problems, BuzzFeed reported.

Despite these issues, Cruz was able to legally purchase the AR-15 he used in the mass shooting. Attorney Jim Lewis told the Sun-Sentinel that the teenager already owned the gun when he moved in with his friend’s family around Thanksgiving, after his mother died this past November.

“It was his gun,” Lewis said. “The family made him keep it in a locked gun cabinet in the house but he had a key.”

Trevor Hart, 16, who knew Cruz from his Spanish class at Marjory Stoneman, told the Sun-Sentinel the alleged killer seemed “a little off” and talked about shooting lizards, squirrels and frogs.

Cruz was expelled from Marjory Stoneman last year for “disciplinary problems,” with one report saying bullets were discovered in his backpack at one point.

One teacher told the Miami Herald that Cruz was banned from entering campus with a backpack.

Officials did not immediately say why Cruz was expelled from the high school.

FLORIDA HIGH SCHOOL FOOTBALL COACH WHO WAS SEEN SHIELDING STUDENTS FROM GUNFIRE DIES

An Instagram page apparently belonging to Cruz showed pictures of guns and knives. Broward County Sheriff Scott Israel said some of Cruz's social media posts were "very, very disturbing."

Additionally, the FBI confirmed Thursday the bureau received a tip this past September about a disturbing YouTube comment by a user named “Nikolas Cruz” that said “I’m going to be a professional school shooter.”

Special Agent Rob Lansky, in charge of the FBI’s Miami division, said the agency investigated the comment, but said it could not identify the user who made the comment. He also said there was no connection found to South Florida.

"No other information was included in the comment which would indicate a particular time, location or the true identity of the person who posted the comment," the FBI said in a subsequent statement.

Fox News' Ryan Gaydos, Elizabeth Zwirz, Shira Bush and The Associated Press contributed to this report.

Lucia I. Suarez Sang is a Reporter for FoxNews.com. Follow her on Twitter @luciasuarezsang