TULSA, Oklahoma - Former Skiatook Superintendent Dr. Gary Johnson and Oklahoma City businessman Rick Enos both entered guilty pleas in federal court to conspiracy to defraud the United States in a bribery investigation.

The two have already pled guilty to state charges that Johnson bought school supplies that were extremely overpriced.

For nearly a decade, Gary Johnson was the Skiatook Public Schools Superintendent.

Johnson had a number of professional and personal financial dealings with Rick Enos.

Friday, the two pleaded guilty to pocketing more than half a million dollars from Skiatook Schools and then lying about it on Johnson's federal income tax.

A 2008 school audit shows Enos submitted invoices to Johnson for supplies, equipment and services at prices inflated as much as 400 percent.

In exchange for his approval on the invoices, Johnson corruptly accepted things of great value from Enos.

According to documents, Enos purchased tickets for Johnson to go to multiple Football National Championship games out of state. Enos also gave Johnson tickets to OU football games and upgraded those seats to box suites.

Records also reveal Enos gave Johnson thousands of dollars in cash to use on personal trips and other miscellaneous events. He even slid Johnson cash inside an OU football program during a game.

None of it was disclosed on Johnson's income tax returns, according to the U.S. Attorney.

The U.S. Attorney says the duo used code words when talking about the money. "Cabinet" meant cash payments of $100 and "large cabinet" referred to $1,000.

Johnson and Enos face up to five years in prison and a fine up to $250,000.

Sentencing was set for February 7, 2013.