Mateen worked for the company for nine years.
After the June 12 massacre, the state found out that the doctor listed on Mateen's evaluation form hadn't conducted his exam. The doctor, psychologist Carol Nudelman, told state officials she never even met Mateen.
The state said a review of G4S Secure Solutions records going back a decade show Nudelman's name appeared on 1,514 exam forms, even though she never did those exams.
The state said when Nudelman retired and another psychologist took over, the company never updated its evaluation forms with the new doctor's name.
The state said that in all of the cases, the armed security guard applicants did receive a psychological exam, it just wasn't from the doctor listed on the form.
Mateen was shot and killed by officers with the Orlando Police Department on June 12 after he opened fire at Pulse, a gay nightclub. The shooting killed 49 people and injured 53 others.