The man behind a mass shooting at a yoga studio was teaching in a Central Florida school district months ago.

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Tallahassee police said Scott Beierle walked into the hot yoga studio Friday, posing as a customer, before killing two people, injuring five others and killing himself.

Since the shooting, information about his past has emerged, including his history working as a teacher in two school districts.

Beierle was once employed in Volusia County, despite having been previously fired from his job as a substitute teacher in Leon County.

>> On WFTV.com: Florida yoga shooter taught at 21 Volusia Co. schools, touched female student's stomach, school says

There were multiple complaints about Beierle's erratic behavior during the application process with Leon County Schools, but he was still approved.

Because of concerns after his firing, the district said it changed how it interviews candidates.

Three Volusia County sisters told WFTV on Monday that Volusia County Schools should also consider changing its policies.

"It was exactly this time last year actually. That could have so easily been us in that situation," Savannah Fulcher said.

"I felt sick, because it was, like, the first moment that I was in his class. I knew something was wrong," Sarah Gillespie said.

Last year, the three sisters said they told a parent and a guidance counselor that Beierle, their Hinson Middle School teacher, made them feel uncomfortable.

"He would just stare at you very deeply and for such a long time, and he would never look away from you," Fulcher said.

They also said Beierle nicknamed and called on female students but not male students.

Worried her daughters and friend weren't being taken seriously, Nicole Gillespie called the school.

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"His Facebook account was sketchy," she said. "I looked it up. I looked up his LinkedIn account. It showed he could not keep a job. I mean, these are all red flags."

A note in Beierle's personnel file shows the school heard from Gillespie.

It outlined her concerns about previous arrests but no conviction for battery.

The note asked if there were any concerns to warrant PSD, which stands for professional standards disqualification.

>> On WFTV.com: Tallahassee shooting victim's father said her death is 'cruel irony'

Shortly thereafter, Beierle was no longer in their classroom. Nine months later, the district terminated him for unprofessional conduct. Five months later, the Tallahassee shooting happened.

"It could have very easily been our schools. It could've been my girls," Nicole Gillespie said. "I just don't even want to think about that. It just hits a little too close to home."

The girls said they want to know why Volusia County Schools moved Beierle instead of terminating him after their complaints.

The district has not given WFTV an answer yet.