O.J. Mayo may have more concerns from his USC days.

The California Attorney General's office is investigating the possible illegal use of an American Express card account that was used to provide thousands of dollars to the USC freshman — instead of being issued to a sickle cell charity, ESPN reported.

Danny Kim, a special agent with the bureau of investigations for the California Department of Justice, told ESPN he was assigned to investigate violations by Tony Hicks, the CEO of the National Organization of Sickle Cell Prevention and Awareness Foundation, a nonprofit organization based in the Los Angeles area.

"We are looking for any financial information that is tied to the sickle cell foundation," Kim told ESPN. "I'm just going to follow the money. I'll have to subpoena or get a warrant to get whatever information I can get."

Hicks is a convicted felon and longtime friend of Rodney Guillory, who was Mayo's mentor and close advisor for the past five years.

These come on the heels of earlier reports of cash and gifts being given to Mayo while at USC.

A former associate of his, Louis Johnson, was on ESPN earlier this month saying Mayo was funneled money by a sports promoter from a professional agent, during and after his high-profile prep basketball career.

Earlier this week, Mayo said he was stunned by the accusations.

“I was overwhelmed,” Mayo told a crowd of reporters Thursday in Orlando, where he was to be weighed and measured as part of the NBA’s pre-draft camp. “I haven’t talked to (Johnson) for a long time — maybe since January.

“I think I was just more upset that something like that was saw on Mother’s Day,” Mayo said. “As the oldest son you don’t want to bring that on your mother on Mother’s Day. I was totally overwhelmed and didn’t understand what was going on.”

Mayo, who declared his eligibility for the NBA draft after one season at USC, has denied receiving any improper funds, and didn’t want to discuss specifics in his first lengthy and open media session since those allegations broke. However, he did say he hasn’t been contacted by the NCAA, which is investigating the matter.

Mayo said he and Rodney Guillory, the promoter who is said to have sent him some of the agent’s contributions, still talk occasionally.

“Just to see how he’s doing, his family,” Mayo said.

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Mayo and agent Calvin Andrews of Bill Duffy Associates parted ways last week, both saying the allegations were too distracting. So now the player whose story has churned so much talk over pro sports agents contacting young prospects is without professional representation of his own.

Teams interested in Mayo leading up to the June 26 draft are scheduling workouts through his Chicago trainer, Tim Grover. Mayo is staying in an apartment there and working out with Grover’s other clients, including Miami Heat star Dwyane Wade.

“I’m just watching him, learning some things from him now,” Mayo said of Wade. “Asking questions, picking his mind a little bit about his first few years in the NBA.”

Mayo said he hooked up with Grover, who also trained Michael Jordan and dozens of other pro athletes, after touring his impressive gym.

“As a basketball player it’s the best facility that you can possibly work out in. It has everything you need, from a barbershop to a pool and a treadmill,” Mayo said. “It has beds. When you get done working out, you can take a shower, lay down and work out again. As a basketball player it’s like heaven.”