He was chronically depressed, beguiled by firearms and violence, an oddball ostracized by peers and prone to angry outbursts.
He experienced, in rapid succession, blows of the sort that can send a disturbed, isolated young man hurtling into a spiral of instability: forced to move out of his lifelong home, spurned by a girlfriend, bounced from school to school, then suddenly losing his mother, his closest companion, to a fatal illness.
In the months before the teenage killer's mug shot and name were splashed across the nation's TV screens and newspaper front pages, he had posted messages online telegraphing his plans and told others about his deadly intentions — warnings that police and federal agents, alerted by tipsters, did not heed.
When, in an unfettered rage and armed with a semiautomatic rifle, he slaughtered 14 students and three educators at his former high school last week, he displayed a special savagery.
Not content to mow down former schoolmates like targets in a shooting gallery, he is believed to have shot some repeatedly, likely at close range, after they were already down.
The combination of pent-up anger and the easy availability of a powerful, fast-firing rifle transformed a scrawny misfit named Nikolas Cruz into a murderous machine, one of a new American archetype: the mass school murderer.
"The guy was filled with rage," said a person who has visited the school building at Marjory Stoneman Douglas High where Cruz fired a squall of more than 100 rounds from his AR-15 into classrooms and down hallways at terrified kids.
The person, who asked not to be named, quoted police as saying that Cruz tried to kill many more. Cruz attempted to shoot out the windows in a third-floor teacher's lounge that gave him a clear sight line to a courtyard below, through which scores of kids were running for their lives. The hurricane-resistant glass cracked but held, saving many lives, the person said.
One fallen student bore the particular brunt of his fury, the source said. Peter Wang, a Junior ROTC cadet whom Cruz apparently knew from the program, held open a stairway door so that other students could escape, witnesses said.
Cruz "not only shot him several times, but when Wang was on the ground, he shot him repeatedly," the person said, quoting police.
Wang was not the only one Cruz shot numerous times. Andrew Pollack, father of slain student Meadow Pollack, 18, told President Donald Trump in a "listening session" at the White House that his daughter had been shot nine times.
Ten days after Cruz's rampage at Stoneman Douglas High in Parkland, much remains unclear about the confessed 19-year-old killer and the circumstances of his family life in the near-idyllic, affluent suburb where he was raised — recently rated as the safest city in Florida.
Only the barest details are known: Cruz was adopted by Roger and Lynda Cruz, as was his younger brother, Zachary, now 18. Because adoption is confidential, it's not known where or when it took place, nor the circumstances surrounding it. Also unknown is when or how Nikolas Cruz's propensity for violence or his fascination with firearms began.
His father, once a partner in a multimillion-dollar printing business in New York in the 1980s before moving to South Florida, died of a heart ailment at age 67 in 2004. Lynda Cruz, who apparently stayed at home to watch over her boys, died in November of a respiratory illness.
But a broad outline has emerged of a troubled life and personality that experts say snugly fits the profile of modern American mass murderers. That's despite economic advantages and a single, widowed mother who, by available reports, was a devoted parent, if overwhelmed by her son's persistent and increasingly alarming behavioral problems.
Contrary to stereotypes, a history of mental illness does not create a mass shooter, experts say. But like Cruz many mass killers exhibit a common set of traits that include depression, troubled family backgrounds, a fascination with guns and violence and aspirations of becoming a soldier, said Peter Langman, a psychologist and author of two books on school shooters. Virtually all are male and most are young.
Not all are loners, Langman said. Like Cruz, many have at least a few friends, though it's not unusual to hear them described as withdrawn or awkward. Those are precisely the words numerous former schoolmates at Stoneman Douglas used to describe Cruz.
"When I met him I knew there was something weird about him, there was something off," said Manolo Alvarez, 17, who shared a 10th grade history class with Cruz. "He was really a quiet kid. He would get bullied a lot."
The murderous sprees are rarely impulsive, the experts say, but prompted by a triggering event, like the breakup of a relationship, said J. Reid Meloy, a forensic psychologist and professor at the University of California, San Diego. Often, too, there is what Meloy refers to as "leakage" — telling or hinting to others about plans to kill.
What drove Cruz to return to his old school and open fire remains a mystery. But often school shooters lack an overriding motivation, and may be propelled by envy or a desire for revenge, in Cruz's case perhaps by perceived slights at his former school.
Cruz was mocked for his odd demeanor and behavior in school and in his neighborhood, according to interviews with close family friends, students and recently released police and mental health reports.
"He would sit on the curb by himself," said former neighbor Rhonda Roxburgh, describing how other kids avoided him at the bus stop. "He was isolated. Nobody wanted to be around him."
At 5-foot-7 and 120 pounds, Cruz was slightly built. People who knew him say he sometimes muttered under his breath, often wore a hoodie over his head and didn't look people in the eye. He rarely seemed comfortable with other kids, said Paul Gold, who lived next door to the Cruz family and remained in touch with Nikolas Cruz up until his mother's funeral in November.
One former neighbor recalled after the shootings that Cruz "had an extremely cold stare." Another described him as "just a little bit creepy."
One contributing factor for his odd affect: Cruz had been diagnosed with attention deficit hyperactivity disorder and autism, though experts caution that neither should be seen as a cause of his attack.
But his problems ranged beyond social or cognitive disabilities. Lynda Cruz struggled to control his behavior at least from the time he was an adolescent, despite periodic interventions by mental health counselors and law enforcement authorities, records show.
"His mother made a major push to have him lead a normal life," Gold said. "But toward the end of her life, she really had given up."
In the past decade, BSO deputies were frequently summoned to their Parkland home, records released by the agency last week show. The complaints, involving both boys, initially seem minor. The first was rock throwing between Nikolas and another boy, followed by reports by Lynda Cruz that Zachary or Nikolas left home without permission on several occasions, threw stuff or hit a door with pool gear, fought with each other or cursed at her.
The incidents grew more serious: Nikolas hit her with a vacuum cleaner hose, and in two disputes over his Xbox video game console threw her against a wall and, another time, punched a wall. In 2014 came a complaint from a neighbor that Nikolas shot at his chickens with a BB gun; the chickens' owner did not press charges, so Lynda Cruz locked away the rifle, police said.
Other neighbors reported him shooting at squirrels, poking into a rabbit hole with a stick and setting his family's dog on another neighbor's piglets. He posted pictures online of bleeding frogs he claimed to have killed.
At Westglades Middle School, Cruz's disciplinary problems grew so acute that he was transferred in February 2014 to an alternative school. In January 2016, he was assigned to Stoneman Douglas High, an A-rated school full of high achievers where he immediately struggled to fit in.
By then, there were signs that Cruz's issues were taking a darker turn.
In February, according to the BSO report released last week, a neighborhood kid reported Cruz had threatened on Instagram to shoot up the school and attached a photo of a small arsenal of firearms. A deputy visited the neighbor and forwarded the complaint to the resources officer at Stoneman Douglas, but it appears no action was taken.
In September 2016, state child-welfare investigators interviewed the family after someone called the state abuse hotline to report that Cruz was cutting himself and had plans to go buy a gun. The agency report noted that the boy had just broken up with his girlfriend, gotten into a fight and drawn a "Nazi symbol" on his backpack.
The Nazi sign and the gun fixation may have been telling signs, said psychologist Langman. Troubled boys and young men like Cruz are drawn to such symbols of perceived masculinity and strength to overcome feelings of impotence.
"My hypothesis is that shooters feel disempowered and they connect with a source of power — and Nazis were powerful," Langman said. "They identify them as hyper-masculine."
The BSO report released Thursday adds an unsettling detail to the September incident: that Cruz might have ingested gasoline in a suicide attempt.
The child-welfare investigators, though, closed the case with no action after concluding that Cruz was not a threat, had not been mistreated by his mother, that he was receiving adequate care from a counselor at Henderson Mental Health, and was attending school. But records and interviews suggest that Cruz stopped going to counseling and sometimes did not take prescribed medication, worsening his behavioral problems.
By early 2017, he may have been entering full meltdown. Lynda's ill health and straitened family financial circumstances that forced a sale of the longtime family home may have played a role.
Though the family home in Parkland was in a relatively affluent suburb, it's unclear how the Cruzes kept up with the lifestyle. What little information has emerged in the public record suggests that the Cruz family, at least at first, enjoyed a certain level of affluence. But money may have gotten tight just before Lynda, by then a widow for 13 years, died in November.
In 1988, Roger Cruz was described in passing in a New York Times story as a partner with sports agent Irwin Weiner in a $40-million-a-year printing business in Mount Vernon, N.Y. Cruz appears to have moved the business to Boca Raton, possibly after Weiner died in 2001, federal court records in a pension case suggest.
Roger Cruz purchased the Parkland home where Nikolas and his brother, Zachary, would grow up, for $94,000 in 1996, two years before the oldest of the boys was born.
The five-bedroom house on a large lot appears grand, although not as grand as those of some neighbors who lived behind gates with private tennis courts. The home sports an arched portico at the front door and a two-car garage off to the side. There's a pool in the backyard, where Nikolas Cruz would practice his aim with a BB gun.
During the boom years of the early and mid-2000s, Roger and Lynda Cruz appear to have used the house as an ATM, taking advantage of its rapidly increasing property value to refinance often and take cash out, real estate records suggest. Between 2001 and 2005, the couple took out five mortgages on the house, rolling one loan into the next mortgage. The first was for $76,625, but the amount escalated quickly to mid and high six figures.
After Roger Cruz died, his business was dissolved, federal court records show. Gold, the couple's neighbor, said he believes Lynda was living in part on a life insurance payout. Lynda had sued a doctor who treated her husband and accepted a $175,000 insurance settlement, though some of that went to legal expenses and a judge awarded the rest to the two boys in the form of an annual payment.
In January of 2017, she sold the family home in a "short sale," likely to stave off repossession. The sale amount, $575,000 was less than the amount of the last mortgage of $760,000 she had taken out on the property after her husband's death.
Cruz told her real estate agent, Erick Mesia, that she could no longer afford the spacious Parkland home. She said "she needed to lower her costs so she could stretch her money longer," Mesia said. By then the home was rundown, he said, calling it "a handyman's special." There were marks on the walls and clutter all about.
"It was a difficult sale because the kids had turned it upside down. It was a mess," said Mesia, whose firm sold the home and helped Lynda Cruz find a smaller, rental townhouse at the MiraLago development in Parkland. "I got the sense the kids were in control," not the mother.
Both boys were upset about moving, he said. Nikolas Cruz knew he wouldn't be able to shoot his beloved BB gun in the backyard of a townhome, Mesia said. (Still, a video later taken by a neighbor showed Cruz, wearing a Make America Great Again hat, doing just that.)
Mesia showed the family roughly 10 homes around Parkland. At first, he said, Cruz wouldn't make eye contact with him. But the young man warmed up after Mesia began showing him pictures of his trips to the Everglades. Soon, they made a plan to go hiking together with Mesia's own son.
"He opened up a little," Mesia said. "He would smile after that. He felt comfortable with me. [His mom] thought that hiking would be great for him."
But Mesia moved to Orlando soon after and they lost touch.
About a week after the move to the townhouse, Nikolas Cruz was involuntarily transferred out of Stoneman Douglas, apparently for assaulting another student, and reassigned to his second alternative school.
Much of his subsequent trouble appears to have been underpinned by conflict over his ex-girlfriend.
Former Stoneman Douglas schoolmates told BuzzFeed News that the transfer came after Cruz got into fights at school with a one-time classmate, Enea Sabadini, whom he accused of "stealing" his girlfriend. Sabadini said Cruz also called him a "n----."
After leaving the school, Cruz continued to threaten to kill Sabadini through Instagram messages, Stoneman Douglas student Dana Craig told BuzzFeed.
Craig said Cruz was "obsessed" with the ex-girlfriend, who told her that Cruz was abusive. The girlfriend, whose name has not been published, broke off the relationship. Craig also believes Cruz was the author of threats directed at her. Craig said she reported the threats to school administrators.
In February 2017, shortly after he had to withdraw from Stoneman Douglas, Cruz legally purchased the AR-15 he would use in the school massacre.
Over the next several months, amid signs that his emotional state was deteriorating, Cruz bounced among several Broward County public schools, including one for students with disabilities, before ending up at an adult education center to get his GED.
His anger seems only to have grown over the months, as he posted threatening messages on social media and participated in online rants against minorities.
In August, CNN has reported, Cruz joined a small, private online chat group that revolved around racist views and firearms. CNN, provided a password to view the chats, reported that Cruz wrote of his hate of immigrants, black people and Jews. He talked about killing Mexicans and gays and chaining up and killing black people. He referred to white women in interracial relationships as traitors.
And he wrote about his birth mother: "My real mom was a Jew. I am glad I never met her."
Still, Cruz could win over people in a low-key way when he wanted to. During this period, he worked at two Dollar Store outlets, one in Coral Springs and another in Parkland. Co-workers described him as quiet but "sweet" and "always happy." One, Brian Halem, was a fellow gun enthusiast, and the two often talked about firearms, he told the Miami Herald.
At least some of the money Cruz earned may have gone to purchase firearms and related gear.
On the chat group, Cruz happily reported where he spent one paycheck: "Guys I got paid 330. I am buying body armor." He posted an image of the receipt in the chat and asked if he could wear the armor to school because of "school shooters," CNN said.
Cruz's life was upended again when his mother died Nov. 1, possibly from pneumonia, though details have yet to emerge publicly. Mesia, the real estate agent, said he believes the loss further damaged Nikolas.
"His mom was his best friend," Mesia said.
If Cruz was feeling bereft and friendless, his mother's funeral did not help. Gold, the neighbor, said he was one of only four people, including Cruz and his younger brother, Zachary, who attended. He said Cruz was upset no one else had shown up.
After her death, Zachary, who had been going to Stoneman Douglas, stopped attending. Unlike his brother, the younger Cruz, a junior, seemed to stay out of trouble after some youthful misbehavior. One friend described him as nice, quiet and a talented skateboarder.
On the day Lynda Cruz died, her cousin, Katherine Blaine, called BSO to report that Nikolas possessed rifles and to ask they take the firearms, though she later denied making the request. BSO turned the weapons over to an unidentified "close family friend."
The friend was likely Rocxanne Deschamps, a former neighbor of the Cruz family who had moved to Lantana in Palm Beach County and agreed to take in the boys after Lynda's death. On Nov. 28, Deschamps made a 911 call to complain that Nikolas had become violent and gotten into a fight with her son. Mother and son said they threw Nikolas out.
Deschamps told the operator that Cruz had pointed a gun previously at his brother and mother.
"I'm afraid if he comes back, and he has a lot of weapons," Deschamps told 911.
But 911 also got a call from Cruz, who complained he'd been attacked.
"The thing is, I lost my mother a couple weeks ago, so I am dealing with a bunch of things right now," Cruz told 911.
Cruz then moved in with the family of a friend from Stoneman Douglas. He was working at the Parkland Dollar Store and attending adult ed in the mornings. After the massacre, the friend's parents, James and Kimberly Snead, said they only tried to help Cruz and had no idea he was so disturbed.
Cruz also told people around him he expected to come into some substantial money from his mother's estate, including his share of the medical insurance settlement and, possibly, Social Security or life insurance payments. But he may have helped himself to some of it right away.
Sometime after his mother's death, a tipster who called the FBI claimed, Cruz withdrew money from her account to buy more firearms. When authorities searched the Snead home, they found six other long firearms belonging to Cruz. The Sneads allowed him to keep the weapons locked up
But people who knew Cruz well grew so alarmed that more than one tried to warn authorities.
On Nov. 30, someone in Massachusetts called BSO to say that Cruz was collecting guns and knives. The caller said Cruz "could be a school shooter in the making," according to the BSO report.
On Jan. 5, a tipster called an FBI hotline to say Cruz may have been planning a school shooting. The tipster, whose name has not been released but is someone close to Cruz and his family, had a wealth of information to impart. She said Cruz had pointed a rifle at his mother.
"Something's gonna happen," the tipster told an intake specialist, adding later: "I just know I have a clear conscience if he takes off and just starts shooting places up."
The FBI did nothing.
Cruz appears to have given serious thought to how he would go about massacring his one-time schoolmates. On the morning of the shooting, he told the Sneads he wasn't going to school because it was Valentine's Day. He wore a Junior ROTC polo, knowing group members wore those on Wednesdays, to blend in when he went back to the school.
Cruz took an Uber to Stoneman Douglas, the AR-15 packed in a soft carrying bag, with extra ammo in his backpack. He strolled into Building 12, fired for six minutes, then dropped the weapon and gear and slipped out of school, camouflaged among his fleeing peers. It's unclear if he always planned to get away; though some mass shooters kill themselves or expect to be shot dead by police, not all do, experts note.
But Cruz seems not to have given any thought to what might happen beyond that point.
Police say he wandered into an adjacent Walmart and a McDonald's. Then he appeared to walk aimlessly into a nearby subdivision, in the opposite direction of home. He was arrested there by a police officer cruising the area in search for the shooter. He offered no resistance.
A Walmart employee was one of the last people to speak to Cruz before his arrest. The young man, who does not want to be named, said he was watching the news from his work station when frightened students started streaming into the store.
He left his desk to see what was going on, and walked over to a student in burgundy sitting on a bench. The employee asked if there had been a shooting. The young man, he later realized, was Nikolas Cruz.
"His response was so nonchalant, like he didn't care," the Walmart clerk said. Nearby, he added, "people were crying."
There was one weird thing, the clerk added. Cruz was talking to someone else — another male student.
"They were chit-chatting. Which I thought was strange," he said, marveling in hindsight at how unaffected Cruz seemed to be.
"His lawyer's saying he's feeling remorse. But when I spoke to him there, it was like nothing had happened," the clerk said. "There's no way he feels bad."
Miami Herald staff writers David Ovalle, Kyra Gurney and Julie Brown and Miami Herald writers Tarpley Hitt, Aaron Leibowitz and Adiel Kaplan contributed to this report.