HARRISON COUNTY, Ohio -- The State Bureau of Criminal Investigation has been called to investigate how a Youngstown man worked as a substitute teacher in the Harrison Hills School district when the district said it never hired him.

Prosecutor Shawn Hervey and Sheriff Mark Miller said they were just blown away by the fact that Frederick Saunders taught 7th graders for several days at Harrison Junior High School.

"It's a public safety concern," said Hervey.

Last week Saunders was charged after police said he hit a picketer with his car.

The district told NEWS9 while Saunders had been a substitute teacher during the strike, they did not hire him.

Hervey said police have Saunders on record saying he did work for Huffmaster security during the strike and that he was getting paid.

"We have some questions about Huffmaster and their practices for public safety because obviously this man was in the school building,” said Hervey.

Meanwhile, Superintendent Jim Drexler said Saunders was never on the payroll.

"We are not exactly sure how he got into the building,” said Drexler. “That's under investigation at this point. We are checking with teachers that were in that building that day and checking with the principle. We are looking for exactly how he got into the building.”

Now the State Bureau of Criminal Investigation is stepping in.

"That's why BCI is being brought in because there are some questions that need to be answered, about how this gentleman had access to students,” said Hervey.

As for Saunders history, Miller said the district assured him every teacher would be checked out.

“We were assured everyone had a background check,” said Miller. “When Mr. Saunders was arrested, we went ahead and did our own background check, and we came up with all this info."

But that information from the background check is not public, so at this point, Saunders history is unknown.

Drexler told NEWS9 he has come up with a plan to make sure this doesn't happen again.

He said the security drivers will escort the teachers into the building, and will have a list of those teachers.

Drexler also said the principal will look at the list and verify their names and their IDs through driver’s licenses.

-Natalie Pasquarella, NEWS9