Here’s what we know so far about the young man authorities say launched the nation’s latest school shooting rampage:
Did Cruz attend Marjory Stoneman Douglas High School?
No, not at the time of the shooting.
Cruz was expelled last school year for “disciplinary reasons,” according to Broward County Sheriff Scott Israel. He did not go into details about the reason for Cruz’s expulsion.
Victoria Olvera, a 17-year-old junior, said Cruz was expelled after a fight with his ex-girlfriend's new boyfriend. She said Cruz had been abusive to his girlfriend.
At the time of the shooting, Cruz was enrolled at a different high school within the Broward County school district, according to school officials.
How was his life at home?
His mother, Lynda Cruz, died in November.
After her death, Nikolas Cruz stayed with family friends in Lake Worth in Palm Beach County. Unhappy at that home, Cruz asked a former classmate from the school if he could move in with him and his family, according to Jim Lewis, an attorney representing that family. Since Thanksgiving, Cruz had been living with them in northwest Broward County, about three miles from the school, Lewis said. He added that Lynda Cruz and her late husband, Roger Cruz, who died in 2004, adopted Nikolas and his half-brother, Zachary, at a young age.
Lewis said Nikolas Cruz was a “little depressed because his mother had just died.”
“But he seemed to be coming out of it and doing better,“ he added.
Cruz had been working at a Dollar Tree store, and he was going to school at an adult education center to get his GED, Lewis said.
Did he post flags about the attack on social media?
On Wednesday, an Instagram account belonging to “cruz_nikolas” was taken down shortly after the shooting. The account included photos of a young man wearing U.S. Army hats posing with guns and knives, his face mostly concealed.
In posts, he appeared to be feuding with others, talked about background checks and plans to purchase a rifle he would outfit with a scope “for hunting.”
Nine months ago, a YouTube user with the handle "nikolas cruz" left a comment on a Discovery UK documentary about the gunman in the 1966 University of Texas tower shooting. The user wrote beneath the YouTube video: "I am going to [do] what he did."
Other past comments by YouTube users with Cruz's name reportedly included one remark in September, saying, "Im going to be a professional school shooter."
What about Cruz’s mental health?
Law enforcement has not answered questions about Cruz’s mental health.
Broward County Mayor Beam Furr told CNN that Cruz had been receiving treatment at a mental health clinic for a while, but that he had not been to the clinic for more than a year.
“It wasn’t like there wasn’t concern for him,” Furr said. “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 used Twitter to address Cruz’s mental health.
“So many signs that the Florida shooter was mentally disturbed, even expelled from school for bad and erratic behavior. Neighbors and classmates knew he was a big problem. Must always report such instances to authorities, again and again!” Trump tweeted.
Did he have ties to a white nationalist group?
Apparently not. The Anti-Defamation League and others initially reported that a spokesperson for the white nationalist group Republic of Florida had said Cruz was associated with his group and took part in training exercises. But the spokesperson, Jordan Jereb, later said he’d been mistaken.
What have teachers and classmates said about Cruz?
The comments have been mixed. Some say he was troubled, others say he was quiet.
Jim Gard, a math teacher at Marjory Stoneman Douglas High School, said Cruz was in his class last year.
“He was quiet in class. I never had any problems,” Gard said.
While Olvera said Cruz was abusive toward an ex-girlfriend, others said he was a loner.
Daniel Huerfano, a student at the school, said Cruz was a shy student; he remembered seeing him walking around with his lunch bag.
“He was that weird kid that you see ... like a loner,” he added.
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Lee reported from Los Angeles; Jarvie reported from Parkland, Fla.
Kelli Kennedy of the South Florida Sun Sentinel contributed to this report.
1:50 p.m.: This article was updated with additional biographical details on Nikolas Cruz.
This article was originally published at 10:55 a.m.