(CNN) -- A Memphis, Tennessee, man faces a 45-count indictment after prosecutors say he took money from teachers who paid to have other people take their certification exams.

Clarence Mumford, 58, allegedly made tens of thousands of dollars from the scheme, which operated between 1995-2010 and involved teachers and aspiring teachers in Tennessee, Arkansas and Mississippi.

"Mumford's conduct has done harm to the systems in which unqualified teachers have been able to teach, to the individual schools, to qualified individuals who could have obtained jobs filled by unqualified teachers, and, ultimately, to a generation of our schoolchildren," said Edward L. Stanton III, U.S. Attorney for the Western District of Tennessee.

It was not immediately clear whether Mumford has retained representation.

According to the indictment, dated Monday, Mumford charged teachers between $1,500-$3,000 per exam. As part of the scheme, he alledgedly collected teachers' IDs and made fake driver's licenses.

The purported scam involved approximately 70 teachers, according to Kristin Helm, spokeswoman at the Tennessee Bureau of Investigations. None were mentioned by name in the indictment.

The tests, which are required to obtain licenses, were written and administered under the auspices of Educational Testing Services, or ETS.

The organization commented on the case in a statement Tuesday.

"ETS's Office of Testing Integrity brought this case to the attention of local authorities and has worked cooperatively with them to bring the alleged perpetrators to justice. Test security and score validity are paramount to ETS, its clients, and test takers. We are continuing to cooperate with authorities and remain committed to providing fair and valid assessments. Due to the ongoing nature of this case we cannot provide further details," it said.