ORLANDO, Fla., June 18 (UPI) -- A three-dimensional portrait of Orlando nightclub killer Omar Mateen is emerging through a series of media reports that depict a man in deep conflict:
Mateen was a chubby kid who endured bullying and grew into a gym rat who one friend said took steroids.
He went from what elementary teachers described as a constant source of classroom disruption to a high school student who graduated early at age 16, with good grades.
Mateen once sought a career in law enforcement, but was fired in part for unnerving comments about guns.
He made sometimes awkward and frightening romantic advances toward both women and men, prompting at least one woman to call him a "stalker." But a gay man said he talked with Mateen on a gay dating app periodically for years, and never felt threatened.
His first wife said Mateen beat her and isolated her in their home; his final words to his second wife came in a text message during Sunday's rampage: "I love you, babe."
Who was Omar Mateen, and what elements from his past could shed light on why he committed the deadliest mass shooting in modern American history?
Those are questions law enforcement officials are only beginning to piece together as Orlando begins burying its dead.
A brush with the law, from the enforcement side
The New York Times reported Saturday that Mateen, 29, who killed 49 people inside Pulse, a gay nightclub in Orlando on Sunday, had been provisionally hired by the Florida Department of Corrections in 2011. Mateen was enrolled in a corrections officer training program, but commanding officers said he was frequently asleep in class and missed days for unexcused absences.
The Times reports the final straw in Mateen's fledgling law enforcement career came when he asked a fellow officer, perhaps jokingly, if he brought a gun to class, would the officer tell anyone?
Two days later, a Virginia Tech student Seung-Hui Cho, barricaded himself inside a building on the university's campus and opened fire, killing 32 people.
In the wake of his poor performance and off-putting comments about guns, Mateen was fired, according to documents released by the Florida Department of Corrections on Friday.
Mateen's supervisor had a chilling explanation.
"In light of recent tragic events at Virginia Tech, Officer Mateen's inquiry about bringing a weapon to class is at best extremely disturbing," wrote Warden Powell H. Skipper.
Romantic encounters were often awkward
The training program washout was not the only unnerving part of Mateen's past to emerge. His first wife has come forward saying he used to beat her and two other women came forward recently, saying Mateen exhibited stalker-like behavior.
One woman told CBS News she met Mateen at a Florida courthouse.
"He came right in front of me, and he looked at me, and he said, 'You're gonna be mine. I want to go out with you,'" said the woman, who CBS did not identify. "And I said, 'No, get out of my face.'"
The woman said Mateen continued to pursue her for some time, despite her repeated refusals. Law enforcement was never involved in the incident and there are no official police reports to verify the woman's story.
The Times said a second woman met Mateen on a dating site after he had married his second wife, and he began sending ominous messages that he was nearby and wanted to see her. The woman said Mateen knew the color of her car and the area where she worked.
Kevin West, of Orlando, said he met Mateen on a gay dating app and the two spoke periodically over the period of a couple years. West said he never met Mateen in person, but Mateen asked him to do so on multiple occasions.
"It wasn't about hookups. He would say, let's meet up for a drink, I come to Orlando a lot," West told the Orlando Sentinel.
The paper reported it has spoken with five individuals in the wake of the shooting who said they encountered Mateen on gay dating sites, though no men have come forward to say they had a physical or romantic relationship with him.
A 'trouble-maker' child went through multiple schools
Delving into his childhood, The Wall Street Journal reports Mateen underwent something of a transformation early in life. Through much of his school years, Mateen was chubby and awkward. He was bullied by classmates.
Teachers described him as a challenge in the classroom, frequently disruptive and seeking attention during elementary school. His third-grade teacher described him as grabby, saying he "inappropriately, impulsively" touched other children.
"Very active, (antsy), constantly moving, verbally abusive, rude, aggressive, much talk about violence and sex, (obscenities) hands all over the place -- on other children, in his mouth."
A middle school teacher reached out to Mateen's parents in a letter, writing Mateen's "attitude and inability to show self-control in the classroom creates distractions and become a main source of difficulty for him."
That teacher's concern echoes his early childhood problems, as well.
The teacher advised Mateen's parents, if he could "improve his self-control, he will find greater social acceptance amongst his peers and thus gain self-confidence."
A former schoolmate gave The Wall Street Journal her fourth-grade yearbook, where a friend had circled a young Mateen's smiling photo and added a caption: "trouble maker."
He would be formally disciplined 30 times in elementary and middle school, according to academic records obtained by The New York Times.
Mateen attended three different high schools, including one where he was disciplined and eventually criminally charged for starting a fight during a math class. Those charges were later dropped.
Perhaps the most well-documented and disturbing incident of Mateen's childhood came at age 14, in the wake of the Sept. 11 terrorist attacks. Mateen, the American-born child of Afghan immigrants, mimicked an airplane exploding to his fellow classmates, cheering the attacks.
Despite the disciplinary problems and uneven behavior, Mateen got his academic act together. He eventually graduated high school in the top half of his class -- and he did so ahead of schedule, at age 16.
Shawn Chegani, a friend who knew Mateen during and after high school said Mateen took up skateboarding and weight-lifting. He said Mateen eventually shed his childhood flab and at one point grew so muscular, Chegani asked Mateen if he'd been using steroids. The friend said Mateen responded, smiling: "Can you tell?"
Others who knew a younger Mateen had a darker recollection of a young man in apparent deep conflict, who never quite fit in.
Former high school classmate Robert Zirkle told the Journal: "We joked that he'd become a terrorist. And then he did."