ORLANDO -- Orlando shooter Omar Mateen's behavioral issues went as far back as elementary school, where his disruptive conduct and "lack of remorse" as a small boy were noted in his school records.
Mateen, 29, went on a rampage at Pulse, a gay nightclub in Orlando on Sunday, killing 49 people and wounding more than 50 others, in the deadliest terror attack on U.S. soil since 9/11.
Mateen's school records paint a picture of a troublesome, angry and inappropriate young boy, who struggled both academically and behaviorally.
The problems shown in school records continued into high school, where Mateen was suspended from school nearly 50 days. As a young man, coworkers described Mateen as angry and said he "could do nothing right in his father's eyes."
Transcripts indicate Mateen began having difficulty in nearly all academic subjects as early as second grade. His poor grades continued through middle school, but improved slightly in high school.
Early school: "Verbally abusive, rude, aggressive"
In 3rd grade at Mariposa Elementary School, a teacher writes that Mateen is verbally abusive, rude, aggressive, and "much talk about violence & sex (obscenities)." The teacher writes that Mateen's hands are all over the place and, "on other children."
A guidance counselor in 4th grade writes that Mateen lacks control, and says he is academically behind "at least two years."
In Mateen's 5th grade school record, a teacher at Mariposa Elementary School writes of Mateen's inability to stay focused, his "lack of remorse," and his opposition.
In a letter to Mateen's father Seddique Mir Mateen in April of 1999, a teacher at Southport Middle School in St. Lucie, Florida, notes Mateen's poor attitude and "inability to show self-control in the classroom." The teacher says Mateen, who was about 13 then, creates distractions, and does little work in class.
"Unfortunately, Omar has great difficulty focusing on his class work since he often seeks attention of his classmates through some sort of noise, disruption or distraction," the teacher writes.
Other incidents include:
- In 3rd grade, a teacher writes that Mateen's parents refuse to sign any consent forms for testing.
- In 3rd grade, a teacher says while singing the school song, Mateen replaced the school name "Mariposa" with "marijuana."
- In 6th grade, Mateen's report card reflects several failed classes. "Summer school" is stamped onto the report card.
- In 7th grade, Mateen was placed in another classroom in order to avoid conflicts with other students.
- In 7th grade, a math teacher says Mateen is doing poorly academically and has "instances of behavioral problems." The record says science and social studies teachers "confirm similar problems."
Later school years: Suspensions, fighting
His behavioral difficulties in school did not end in his early years.
Middle and high school records suggest that Mateen was suspended from school a total of 48 days. The records do not specify what the suspensions were for, except FIT (fighting with injury) and ORV (other rule violation).
Five of Mateen's suspended days were spent in school, and 43 were spent out of school, according to a handwritten note in the record. The suspensions appear to come from three different schools Mateen attended: Martin County High School, Spectrum Alternative High School, and Stuart Middle School.
Records show that he earned his high school diploma from Martin County Community Adult High School.
In October 2006, in a background check by Martin Correction Institution where he briefly worked, a handwritten "letter of explanation" from Mateen described a 2001 altercation when he was 14 years old.
In the handwritten note, Mateen writes that he got in a fight with a fellow student in math class at Martin County High School. After the fight, the school resource officer released him to his parents. Mateen writes that he was not handcuffed, or brought to jail. He says that the charge of battery and the charge of disturbing school function were dropped.
"It has been five years since the fight occurred and I have not gotten into any altercations," he writes.
It is believed Mateen left Martin High School after that fight, and began attending Spectrum Junior/Senior Alternative High School.
Early adulthood: Fired from jobs, alleged steroid use
Mateen's erratic behavior persisted into adulthood.
Documents from the Florida Department of Corrections on Mateen show that he was an employee at Martin Correctional Facility from October 2006 until April 2007. Termination records show that in April 2007, Mateen was fired from an unspecified job for "reasons other than misconduct connected with the work."
The St. Lucie County Sheriff's Office has previously confirmed that it wanted Mateen transferred out of a Florida courthouse in 2013 after they said he made inflammatory remarks about women and Jews and then praised the Fort Hood shooter.
However, one former coworker at least, did not see Mateen having behavioral issues in the workplace -- although he was still troubled.
Margaret Barone was Mateen's supervisor at the GNC in Jensen Beach, Florida, from February 2006 to November 2006.
She told CBS News investigative producer Laura Strickler that Mateen was a good employee, but claimed he had started using steroids after leaving the job.
Barone said that Mateen left the position at GNC to pursue law enforcement jobs.
In an application for a college criminal justice program, Mateen wrote he wanted a career in law enforcement as far back as 2005, CBS News homeland security correspondent Jeff Pegues reported.
After he left GNC, Barone said Mateen started taking steroids and "he blew up" and became "huge."
Barone said during the alleged steroid use Mateen's arms went from 20 inches around to 40 inches around. She said he talked about doing steroids and was "doing too much," and continued to come into the store to buy supplements.
Barone told Strickler that another employee, who was also Muslim, went out with Mateen a number of times. The employee told Barone that Mateen drank so much he would often black out. This former employee said that Mateen did not treat girls well, and became "crazy and violent" when he drank.
Mateen's ex-wife has also accused him of beating her and being mentally ill.
The other employee also allegedly told Barone that she thought Mateen was gay.
Asked about his son's sexual orientation on Tuesday, Seddique Mir Mateen, Mateen's father, said he did not believe his son was gay.
"To me, that is wrong," Seddique Mir Mateen told CBS News correspondent David Begnaud.
Mateen's father said he learned of the speculation of his son's sexuality from news reports, but as far as he was concerned, "I didn't see any of it and I don't believe that was the case."
According to Barone, when Mateen worked for her, "He could do nothing right in his father's eyes."
Barone said she talked to Mateen's father many times and said his father would complain that his son didn't have any direction or know what to do in life.
Barone told Strickler that while she allowed Mateen to do his prayers in the back of the GNC store, she said he never said anything about 9/11 or sympathizing with radical Muslims.
Claimed ISIS affiliation
The FBI is characterizing the mass shooting as both a terrorist attack and a hate crime, CBS News' Paula Reid reported.
A source familiar with the investigation tells CBS News that Mateen referenced the Islamic State of Iraq and Syria (ISIS) in a Facebook message posted moments before the shooting.
"You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance [sic]," Mateen wrote, according to the source.
"In the next few days you will see attacks from the Islamic State [ISIS] in the usa," the post said.
Mateen also declared allegiance to ISIS and leader Abu Bakr al-Baghdadi in 911 calls he made during the attack early Sunday morning, a U.S. intelligence source told CBS News.
CBS News investigative producers Laura Strickler and Jennifer Janisch contributed to this report