RALEIGH, N.C. — Hundreds of invoices show lots of transactions between Wake County Schools' Transportation Department and a Wilson-based supplier Barnes Motor and Parts. Those dealings are now under scrutiny by the State Bureau of Investigation, causing a major shake-up.

Four years ago, 12 percent of Wake County schools' transportation supply budget went to the Wilson-based supplier. Last year, that number was up to 66 percent, totaling more than $4 million. No other supplier even came close.

Some invoices describe the products ordered while others did not. SBI agents will look closely at the invoices, the descriptions, and what was actually received.

The school system suspects it overpaid Barnes Motor and Parts and its Raleigh office. There are also concerns the transportation department did not follow state purchasing laws. Orders for the same item were sometimes separated to keep the total for each invoice under $2,500 -- the maximum for parts not under state contract.

A representative from Wake County Schools told WRAL that way of doing business is circumventing the state contract process, which is wrong.

School board members have talked about the investigation, and Wake Superintendent Bill McNeal has talked about sending a message.

"We have no tolerance for ethical or criminal breeches," he said.

Last week, three longtime employees -- Carol Finch, Pam Stewart and Angela Malloy-Sanders -- resigned from their positions with the schools' transporation department. This week, another employee, Vern Hatley, was re-assigned.

Since April, laws for state contracts have loosened, but officials said this case may go back months and even years. Barnes Motor and Parts said it cooperated with the school system audit. Currently, no one has been criminally charged.