A man who gained media attention after claiming he saved students from a mass shooting while working as a substitute teacher never worked at the school, officials say.
He recounted stories of barricading children from an English class into their room, telling them to find cover and muffle their screams to avoid detection.
However, an investigation by the Texas Tribune has revealed his supposed heroics are likely a fiction.
Local police told the news website the shooting had been confined to art classrooms and there were no English classes being held in the vicinity.
Meanwhile, school district officials said they had no record of his employment and are confident no one of the name David Briscoe was on campus at the time of the attack.
“We are extremely disappointed that an individual that has never been a part of our school community would represent themselves as a survivor of the mass violence tragedy that our community endured,” said Leigh Wall, the superintendent of Santa Fe Independent School District said.
“This situation illustrates how easily misinformation can be created and circulated, especially when the amount of detailed information available is limited due to the still ongoing investigation.”
In the wake of the shooting, Mr Briscoe appears to have contacted several media outlets to claim he was involved in the tragedy.
“It was simultaneous,” Mr Briscoe had told CNN. “I barricaded the door with desks and tables and shut the lights.
“Honestly, it felt like hours before we got out of the school, but one of my students said it was 30 to 45 minutes.”
His story went into grisly detail, including claims he heard the sound of what he supposed was a child getting shot, followed by “groaning”.
He went on to contact the Tribune in April this year, asking reporter Alexandra Samuels if she would consider a follow-up story relating to a string of recent suicides by mass shooting survivors.
In a subsequent phone call, Mr Briscoe reportedly told Ms Samuels he had given up teaching and moved out of Texas as a result of the trauma he suffered.
He claimed he had given a speech on his experience at a high school in Orlando, Florida, an event the principal of the school said never took place.
Later asked if he could help fact-check some of his claims, Mr Biscoe claimed one of his employees had been impersonating him during the interview and on social media, denying he had given an interview. The Twitter account he used to first contact the Tribune has since been deactivated.
Dimitrios Pagourtzis, at the time a 17-year-old Santa Fe High School student, has been charged with 10 counts of murder in connection to the shootings. He is currently awaiting trial.