As early as third grade, the Florida nightclub shooter talked frequently about sex and violence and before finishing high school was suspended for a total of 48 days, including for fighting and hurting classmates, school records showed.
In the years since, other people reported having disturbing run-ins with Omar Mateen, including a bartender who said he stalked her nearly a decade ago and sent so many uncomfortable Facebook messages that she blocked him on the social network.
Mateen, whose attack on the Pulse nightclub left 49 people dead and 53 wounded, enrolled in Florida public schools after his parents moved in 1991 from New York City to Port Saint Lucie, on Florida's Atlantic coast.
Teachers "couldn't seem to help him," said Dan Alley, retired dean of Martin County High School. "We tried to counsel him and show him the error of his ways, but it never had the effect that we were hoping for."
The 29-year-old son of Afghan immigrants was killed Sunday in a shootout with police as they moved into the club.
At least some of his suspensions were for fighting that involved injuries. Others were for unspecified rules violations, according to the records.
For elementary and early middle school, Mateen attended class in neighboring St. Lucie County, where teachers said he was disruptive and struggled academically.
A third-grade teacher wrote that he was "very active ... constantly moving, verbally abusive, rude, aggressive." The teacher described "much talk about violence & sex," with Mateen's "hands all over the place - on other children, in his mouth."
The same teacher wrote that Mateen and another student sang the words "marijuana, marijuana" rather than the school's song, "mariposa, mariposa."
In seventh grade, school administrators moved Mateen to another class to "avoid conflicts with other students." That same report said Mateen was doing poorly in several subjects because of "many instances of behavioral problems."
In a 1999 letter to Mateen's father, one of his middle school teachers wrote that the boy's "attitude and inability to show self-control in the classroom create distractions and become a main source of difficulty for him."
"Unfortunately, Omar has great difficulty focusing on his classwork since he often seeks the attention of his classmates through some sort of noise, disruption or distraction," the letter said.
Mateen attended high school and part of middle school in Martin County, spending time on three campuses in all, including one alternative facility.
He withdrew from Martin County High School in 2003 and eventually graduated from Stuart Adult Community High School with a standard diploma, records show.
In 10th grade, he received a five-day suspension on Sept. 13, 2001 - two days after the terrorist attacks on the World Trade Center and Pentagon.
The records offer no details except to call it a "rule violation." But in recent media reports, classmates have said it was because he celebrated the attacks.
Alley said Mateen's father, Seddique Mateen, "would not back up the school, and he would always take his son's side."
Mateen's father has suggested his son had anti-gay feelings after recently seeing two men kiss. But others have said he was a regular at the Orlando club and that he tried to pick up men there.
Dina McHugh recalled Mateen taunting her about being a lesbian when they were in middle school, before she was even aware of her own sexual orientation.
Now openly gay, McHugh said Mateen's teasing more than 16 years ago stung deeply enough that she paid him back by kicking him in the crotch.
In an interview Friday near the Port St. Lucie supermarket where she works, the 29-year-old McHugh said a teacher who saw the fracas took both students to the dean's office. McHugh said they were both scolded and told to leave each other alone.
"He was the jerk of the class," said McHugh, who attended Southport Middle School with Mateen from 1997 until 1999. "He just got on everybody's nerves. He found a way to get underneath everybody's skin."
After high school, Mateen attended Indian River Community College, graduating in 2006 with a degree in criminal justice technology.
It was around that time that he met a bartender from Fort Pierce.
"He was one of those guys who wouldn't leave me alone," Heather LaSalla told an Associated Press reporter Friday in an interview in the doorway of her home. She worked at a bar in Port St. Lucie at the time, and Mateen started coming there, mostly by himself.
"He was always like a loner," LaSalla said.
The tone of Mateen's Facebook messages made LaSalla uncomfortable, she said, but she never filed a criminal complaint.
She ran into him again at a park in November while she was with her young son and Mateen was with his, she said.
"He still had that weird vibe to him," LaSalla said, but she did not feel threatened as Mateen told her had a wife and talked about his son's soccer league.
Asked whether she believed Mateen was gay, LaSalla said she "never noticed." She said he never exactly propositioned her in his messages.
A year after graduating from community college, Mateen passed a psychological evaluation as part of his application to be a private security guard.
Florida records show he was deemed mentally and emotionally stable in September 2007 before he went to work for the Wackenhut Corp., later renamed G4S Secure Solutions. The papers indicate he took a written psychological test or had an evaluation by a psychologist or psychiatrist.
In a 2007 application for a gun license, he said he had never been diagnosed with a mental illness or any history of alcohol or substance abuse.
As part of the application, he had a medical exam. The paperwork was signed by Dr. Syed Shafeeq Rahman, who is also the imam at the Fort Pierce Islamic Center and has close ties to Mateens' family. Mateen's father was a board member at the mosque with about 120 members.
Rahman declined to discuss his relationship with Mateen and his father.
G4S has said that Mateen was subjected to "detailed company screening" when he was recruited in 2007, and was re-screened again in 2013 with no adverse findings.
But as a security guard, Mateen ran into trouble.
Mateen was removed from an assignment at the St. Lucie County courthouse in 2013 after he made inflammatory comments about women, Jews and a shooting at Fort Hood, Sheriff Ken Mascara said.
The FBI investigated Mateen over those comments and again in 2014 because of his ties to a Syrian suicide bomber who went to the same mosque. Both cases were closed without the agency taking action.
The FBI has been investigating how much Mateen's second wife, Noor Salman, knew about the plot.
On Friday, a person familiar with the FBI's investigation of Mateen said his wife text messaged him on the night of the shooting, asking Mateen where he was and telling him she loved him.
The person was not authorized to publicly discuss the probe and spoke on condition of anonymity.