The principal at August Ahrens Elementary School and a teacher have been placed on leave while the state Department of Education investigates an allegation of financial impropriety.

The action comes three months after the state schools superintendent vowed to set up a fraud-reporting hot line and increase the department’s internal auditing arm.

Florentina Smith, principal of the 1,200-student elementary school in Waipahu, is being investigated by the department’s internal auditor for allegedly directing the unidentified teacher to file a per diem reimbursement claim for training that never occurred, sources told the Star-Advertiser Wednesday.

Smith could not be reached for comment Wednesday.

If the allegations prove true, it would be the fourth case of financial impropriety in the department since 2010, and Smith would be the highest-ranking public school official to be implicated.

A member of August Ahrens’ administrative staff is also on leave, under investigation for allegedly telling the teacher not to talk about the incident, sources said.

The amount of money involved in the reimbursement claim isn’t known.

Department officials did not respond to repeated requests for comment Wednesday.

Board of Education Chairman Don Horner, who has been urging better auditing practices at the department, could not be reached for comment.

The investigation at August Ahrens comes three months after the former business manager at Waipahu High School pleaded guilty in state court to stealing nearly $500,000 from the school over six years.

His case followed two other thefts by school employees.

A Pearl Ridge Elementary School secretary was convicted last year of stealing nearly $70,000. In December 2010, a Lehua Elementary School secretary was ordered to perform community service after stealing $13,000 from fundraisers and donations collected for student programs.

In November, Schools Superintendent Kathryn Matayoshi said the department was working to ensure similar thefts didn’t happen.

Matayoshi said at the time that the department planned to set up a fraud-reporting hot line, offer training to help staff quickly spot possible theft, increase its internal auditing arm and review policies to determine whether any needed to be strengthened.

The department was to have sent a letter on Tuesday to parents of students at August Ahrens about the administrative changes.

Hanh Nguyen, one of the vice principals at Pearl City High School, was appointed interim principal on Monday, when he held a staff meeting.

He told teachers and staff that "this is a personnel matter," Nguyen said Wednesday. "Not a whole lot can be disclosed because of privacy, confidentiality."

But he told the teachers and staff that, "I’m here to support them. Our mission doesn’t alter. We have to educate our students."