Meanwhile, Cruz made his first court appearance, shackled and "cowering in fear" as the Daily Mail described it. He was wearing an orange jumpsuit and both his hands and ankles were bound.

The ADL said ROF leader Jordan Jereb told them Cruz was associated with his group. Jereb, who is based in Tallahassee, said Cruz was brought into the group by another member and had participated in one or more ROF training exercises in the Tallahassee area, the ADL said.

Law enforcement officials haven't confirmed the connection, Jereb did publicly disavowed Cruz and his actions, but confirmed that Cruz did train with his militia, according to the New York Post.

The eader of the group told ABC News he has not spoken to Cruz in “some time” but said "he knew he would getting this call." He would not comment further but emphasized that his group was not a terrorist organization.

Cruz, a 19-year-old orphan with a troubled past, a fascination with weapons and resistance groups, and an AR-15 rifle, was charged with 17 counts of premeditated murder Thursday morning after being questioned for hours by state and federal authorities following the deadliest school shooting in the US in five years.

Cruz's unsuspecting former classmates thought they were having another drill Wednesday afternoon when a fire alarm sounded, requiring them to file out of their classrooms. That's when Cruz, equipped with a gas mask, smoke grenades and multiple magazines of ammunition, opened fire with a semi-automatic weapon, killing 17 people and sending hundreds of students fleeing into the streets. Cruz was able to leave the scene and blend in, but was apprehended about an hour after he stopped firing.

The ROF has mostly young members in north and south Florida and calls itself a "white civil rights organization fighting for white identitarian politics” while seeking to build a “white ethnostate” in Florida.

Three former schoolmates of Cruz told ABC News that Cruz was part of the group. They claimed he marched with the group frequently and was often seen with Jereb, who also confirmed to ABC News that Cruz was, at least at one point, part of that group.

In an interview with ABC News’ George Stephanopoulos, an attorney for the family that had taken Cruz in for the past few months said Cruz was “depressed” following his mother’s death but he had been going to therapy.

The family is still “shocked,” he said, that Cruz would allegedly engage in mass violence.

“They indicated they saw nothing like this coming,” Lewis said. “They never saw any anger, no bad feelings about the school.”

A family that had taken Cruz in after the November death of his mother was aware he owned a legally purchased AR-15 within the past year from a federally licensed dealer, but they said it was locked in a safe.

“He brought it into the home and it was in a locked gun safe,” the lawyer said. “That was the condition when he came into their home that the gun was locked away.”

Cruz had a history of mental illness and violent threats that had led to him getting in trouble repeatedly at school. One student who participated in Junior ROTC with Cruz described him as a “psycho.” Cruz was a well-known weapons enthusiast, the student said, who once tried to sell knives to a classmate.

Cruz even reportedly threatened to shoot up the school...

"About a year ago I saw him upset in the morning," student Brent Black told ABC News.

"And I was like, 'yo what’s wrong with you?'

And he was like 'umm, don’t know.'

And I was like 'what’s up with you?'

He's like 'I swear to God I'll shoot up this school.'

And then I was like 'watch what you’re saying around me,' and then I just left him after that.

He came up to me later on the day and apologized for what he said."

But despite these threats, no action was taken other than to bar him from campus and to instruct teachers not to let him near campus with a backpack. Broward County Sheriff also said "disturbing" content was found on Cruz's social media accounts. The photos released so far depict Cruz with an arsenal of weapons - a common sign among school shooters. the Columbine shooters also took photos of them posing with weapons. 

In a shocking admission, an FBI official also said Thursday that they were warned - not once, but twice - about the shooter. One of the warnings came in September, from a bail bondsman in Mississippi who alerted the feds about an alarming online message Cruz wrote saying he was 'going to be a professional school shooter'.

Ben Bennight, a Youtube commentator, said he alerted the FBI to a comment shared by Cruz on one of his YouTube videos back in September. He says the FBI was quick to respond to the concerning statement, arriving at his office the very next day to find out if he knew anything about Cruz, but the bureau was ultimately unable to ascertain his identity.

Police say they're "already dissecting" his social media posts.

“We have already begun to dissect his websites and things on social media that he was on, and some of the things that have come to mind are very, very disturbing,” Israel said.

A cowering Cruz was decided to be held without bail during his first court appearance on Thursday, where he was officially charged with 17 counts of premeditated murder.

The 19-year-old who killed 17 and injured more than a dozen in a shooting at Marjory Stoneman Douglas High School in Parkland, Florida on Wednesday did not speak in court today, other than to confirm his name with a polite 'yes ma'am' to the judge. Mostly, he he kept his gaze to the ground.

He wore an orange jumpsuit, and had both his hands and ankles shackled. As he took the podium to speak to the judge over livestream video from the Broward County jail, a handful of sheriff's deputies and prison officials gathered around, as the Daily Mail reported.

A female attorney representing Cruz rested a reassuring hand on his shoulder while the charges were read.

A Broward County official said Cruz has been on suicide watch since being taken into custody because he has threatened to kill himself.

He was initially taken to the hospital for "labored breathing"...police then spent most of the night questioning Cruz about his motives and the possible role of anybody else.

The shooting was the 30th mass shooting in the US this year, and both Connecticut senators Chris Murphy and Richard Blumenthal released videos of them making strident calls for gun control.

Florida Gov. Rick Scott speaks to reporters at a Thursday morning press conference about the shooter, accompanied by Broward County Sheriff Scott Israel and Parkland School Superintendent Robert Runcie.

In another admission that calls into question how, exactly, Cruz managed to legally buy an assault rifle,  Broward County Mayor Beam Furr also revealed that Cruz had been getting treatment at a mental health clinic for a while, but hadn't been back to the clinic in more than a year.

"It wasn’t like there wasn’t concern for him," Furr told CNN. "We try to keep our eyes out on those kids who aren’t connected. … In this case we didn’t find a way to connect with this kid."

President Trump addressed the nation this morning after the shooting, which was the eighth largest mass shooting in US history.

Cruz had been suspended from the school from fighting his ex girlfriend's new boyfriend and was depressed and having girl problems at the time of the shooting.

Trump ordered all flags to fly at half-mast Thursday...

* * *

Meanwhile, the Mail has published a detailed list of all the alleged "warning signs" about Cruz and his intentions that were simply missed or ignored...

1. 'I'm going to be a professional school shooter'

Nikolas Cruz left a comment on a YouTube video back in September using his own name that simply read: 'I'm going to be a professional school shooter'

2. FBI was warned about the comment but couldn't identify him

Vlogger Ben Bennight alerted the FBI to the comment shared by Cruz. The FBI was quick to respond, arriving at his office the next day but only after Bennight called a local field agent, revealing his initial attempts to send in a screengrab of the comment failed when the email address he found listed on the agency's website came back with a domain error saying it did not exist. The FBI was unable to identify the person who posted the comment.

3. Bought an AR-15 age 18

After Cruz's mother died, he eventually moved in the the family of a former classmate, where he brought his AR-15 which was kept in a locked cabinet that he had the key to. He was able to purchase the rifle in the past year and passed a required background check. Federal law allowed people 18 and over to legally purchase long guns. At 21, people can legally buy handguns from a license dealer

4. Troubling Instagram page

Cruz's Instagram page is filled with disturbing posts of what appears to be himself showing off with weapons with his face covered, asking for advice on buying firearms, and making racist comments about Muslims.

5. Was a member of a white nationalist group and came to training exercises

Jordan Jereb claims that Cruz was a member of the Republic of Florida, which aims to make Florida its own white-entho state. Jereb claimed Cruz, who was adopted, was brought up in the organization by another member and he reportedly carpooled to at least two training exercises held by the group.

6. Boasted about hurting animals

Students who say they knew Cruz claimed he liked to kill animals.

'He was crazy because he liked to kill small things, like little animals - frogs and other animals like that and he just had a crazy mind,' one told 10ABC news.

Another classmate claims he would tell him he shot rats with a BB gun.

7. Took knives and bullets to school

Former classmate Joshua Charo, 16, said all he 'would talk about is guns, knives and hunting'.

Another student said he started selling knives out of a lunchbox when he started high school.

8. Was banned from carrying a backpack

Jim Gard, a math teacher, who had Cruz in his class last year, said he believes the school sent out an email warning teachers he shouldn't be allowed on campus with a backpack.

'There were problems with him last year threatening students and I guess he was asked to leave campus'.

9. Expelled for fighting

The deeply troubled 'loner' was expelled last year for 'fighting over his ex-girlfriend' with her new boyfriend.

10. Abusive to his ex-girlfriend

Students claim the gunman was abusive to his girlfriend

11. Stalked another girl

Mr Gard also claimed that he was taken with another student 'to the point of stalking her', while another student who claims to have been friends with Cruz said he had to cut him off because he started 'going after' and 'threatening' a female friend of his.

12. Peeping Tom

Neighbor Christine Rosburgh said she, and all the other neighbors, were terrified of the teen who would bang his head against a cement wall if his legal guardians tried to send him to school.

She also claims she caught him peeking in her window and when she confronted him, he said he was looking for golf balls.

'I said, "This isn't the golf course".

13. Stopped his mental health treatment

Cruz had been getting treatment at a mental health clinic, but stopped about a year ago and dropped off the radar. He was showing signs of depression.

Broward County Mayor Beam Furr said: 'It wasn't like there wasn't concern for him. We try to keep out eyes out on those kids who aren't connected... In this case, we didn't find a way to connect with this kid.'

14. Possible fetal alcohol syndrome

Natalie Brassard, a program director at the non-profit FASCETS, which works with FASD children, said some of Cruz's characteristics 'suggest that he might have been living with an invisible brain-based condition - it could have been FASD or many others.'

Conditions of FASD can range from mild to severe but can include learning disabilities, intellectual disability or low IQ, poor reasoning and judgment and a host of other issues.

15. Orphaned

Cruz's adoptive mother, Lynda Cruz, 68, died of pneumonia in November last year. She was one of the only people that was remotely close to Cruz. His adoptive father Roger Cruz died of a heart attack several years ago.

After his mother died, he and his brother were left in the care of family friend Barbara Kumbatovich, of Long Island, New York, but unhappy there, he moved in with a former classmate in a mobile home park in northwest Broward.