A day after being accusing of killing 17 people at the Marjory Stoneman Douglas High School, more has been revealed about alleged shooter Nikolas Cruz, including the fact that he may have been a member of a white nationalist group.

Broward County Sheriff Scott Israel said on Wednesday that the 19-year-old Cruz was expelled from Marjory Stoneman Douglas High School for disciplinary reasons.

This was before 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, according to law enforcement.

Runcie says he did not know of any threats Cruz posed to the school. However, from bizarre social media posts to a troubled family life, some are asking why no one saw the warning signs.

Cruz posted to his Instagram page photos of guns, a kerchief covering his face and even brandishing a knife.

On Wednesday night, the FBI and law enforcement searched the home where he lived.

"The alleged shooter lived here for about the last three months. His mother had died back in November of this last year and this family took him in. And he knew another student at Douglas and that's how they met and they offered the home and tried to help the kid out because he really didn't have any other place to stay," said Jim Lewis, attorney for the family who took in Cruz.

A student told the Associated Press Cruz was expelled from Marjory Stoneman Douglas High School after a fight with his ex-girlfriend's new boyfriend. Victoria Olvera, a 17-year-old junior at the high school, described Cruz as abusive to his girlfriend.

"I think everyone had in their minds if anybody was going to do it, it was going to be him," she said.

School administrators say he started to attend another school in Broward County after his expulsion and classmates called Cruz a loner.

"I had class with him sophomore year. I got assigned to a group project with him and he started talking to me and told me how he got kicked out of two private schools. He was held back twice. He had aspirations to join the military. He enjoyed hunting. He always just seemed very quiet and strange," Brandon Minoff said.

However, another student described Cruz as someone who was always nice.

"He was in my junior ROTC class. And from what I knew from him personally, just me and him, he seemed pretty normal to me. I was always nice to him. He was always to me. Me and Gabriela go on movie dates. He is the cashier at the dollar store. When I knew he was nice," Jonathan Guimaraes told CNN Tonight.

Lewis said the family who took in Cruz say they knew he owned an AR-15 but made him keep it locked up in cabinet.

He did have a key however.

"They are shocked about these allegations and nothing that they saw in this young man. He was a pretty meek, mild kid. Small kid. Nothing that they saw in this kid would give them any reason to believe that anything like this was possible," Lewis said.

Broward County Mayor Barbara Sharief says Cruz was getting treatment at a mental health clinic for a while, but had not been back to the clinic in more than a year.

On Thursday, a leader of a white nationalist militia said Cruz was a member of his group and participated in paramilitary drills in Tallahassee.

Jordan Jereb told The Associated Press on Thursday that his group, the Republic of Florida, wants Florida to become its own white ethno-state. He said his group holds "spontaneous random demonstrations" and tries not to participate in the modern world.

Jereb said he did not know Cruz personally and that "he acted on his own behalf of what he just did and he's solely responsible for what he just did."

He also said he had "trouble with a girl" and he believed the timing of the attack, carried out on Valentine's Day, was not a coincidence.

Also on Thursday, Cruz was charged with 17 counts of premeditated murder and he is being held without bond.

The Associated Press contributed to this story.