Memphis Grizzlies guard O.J. Mayo has communicated with the U.S. Attorney's office amid allegations that federal laws may have been violated when Mayo's former adviser gave him money and gifts during his high school and college career, according to a source with knowledge of the case. The source would not elaborate on Mayo's contact with federal authorities.

The development comes as the NCAA is looking into whether Mayo's brother Todd Mayo, a high school basketball player, also received improper benefits.

Dan Goodman, the deputy criminal chief of the U.S. Attorney's office for the Central District of Los Angeles, said: "We couldn't comment whether there's an ongoing investigation or not."

Federal authorities are investigating Rodney Guillory, the adviser, for possible tax evasion and misuse of charitable organization funds, according to reports.

The NCAA, Pac-10, FBI, IRS and U.S. Attorney's office have been interested in speaking with Mayo since they began investigating questions raised in a May 2008, "Outside the Lines" report that detailed how Mayo had accepted about $30,000 in cash and other benefits from Guillory.

The "Outside the Lines" report included an interview with former Guillory associate Louis Johnson, who said he helped Guillory provide Mayo with money, meals, clothes, a flat-screen television and other goods until 2008, shortly before Mayo finished his freshman season at USC. The gifts and cash began when Mayo was in high school at North College Hill in Cincinnati.

The 6-foot-4 Mayo left USC after his freshman season and was taken with the third pick in the NBA draft by the Minnesota Timberwolves. After a trade, he played this season with the Grizzlies and averaged 18.5 points a game.

While Mayo has responded to inquiries from law enforcement, for more than a year he has declined requests to set up a meeting with NCAA investigators looking into the allegations. After the "Outside the Lines" report aired, Mayo told reporters he planned to cooperate with the NCAA. Mayo could not be reached for comment.

In a concurrent investigation, federal authorities are investigating whether Bill Duffy Associates Sports Management (BDA Sports) funneled up to $250,000 to Guillory in exchange for Mayo signing a contract with Duffy's agency.

After he declared for the NBA draft, Mayo signed with agent Calvin Andrews of BDA Sports, but they split shortly after the "Outside the Lines" report aired. Andrews was suspended from representing players for one year by the National Basketball Players Association in connection with the Mayo case. Mayo is now represented by agent Leon Rose.

In the latest development of the NCAA's investigation, the enforcement staff wants to know whether Guillory paid for a flight for Mayo's younger brother, Todd Mayo, from Los Angeles to Columbus, Ohio, in 2007 while O.J. Mayo was in summer school at USC, Johnson's attorneys Anthony Salerno and David Murphy confirmed. The attorneys also confirmed that NCAA investigators want to know whether Guillory paid for Todd Mayo's cell phone service while O.J. Mayo was in college.

Todd Mayo is a basketball player himself. This past season he averaged 23 points a game as a junior at Houston High School in suburban Memphis. Attorneys for Johnson confirmed on Wednesday that NCAA investigators asked Johnson about two documents from the "Outside the Lines" report that are linked to Todd Mayo.

One of the documents the NCAA is reviewing is a copy of a Nov. 4, 2007 T-Mobile invoice charged to a nonprofit foundation run by Guillory. Johnson told "Outside the Lines" that Guillory paid $192.33 for Todd Mayo's cell service.

Johnson said Guillory paid for Todd Mayo's phone bill as a favor to O.J. Mayo and not as an attempt to "recruit" the younger Mayo. Murphy said even though Todd was the recipient of the phone service, Guillory paid it to curry favor with the older Mayo brother. "Given Todd Mayo's relationship to O.J., any benefit that was given to Todd Mayo could reflect upon the [NCAA investigation] as it pertains to O.J.," Murphy said.

Johnson's attorneys further confirmed that the NCAA has a copy of another document that "Outside the Lines" obtained: a handwritten receipt with Todd Mayo's name on it, dated Aug. 2, 2007. The receipt is from L.A. Traveling Tours for the amount of $395.80 ($345.80 for the ticket and $50 commission, the receipt says).

Johnson said Todd Mayo was visiting his brother, who attended summer school at USC during the summer of 2007. Johnson said he was with Guillory and Todd Mayo when Guillory purchased in cash the one-way ticket for Todd Mayo from Los Angeles to Columbus. Todd Mayo lived in Ohio. Even though Guillory paid for the ticket, according to Johnson, the receipt shows the purchaser's name as "Ovinton Mayo." Johnson said Guillory made sure it appeared that O.J. Mayo had paid for his brother's flight home.

"He needed [the receipt] to say that O.J. bought the ticket," Johnson said Wednesday. "It doesn't have Rodney's name on it ... because Rodney was deemed a runner by the NCAA and because there was a lot of scrutiny on him because of his relationship with O.J."

The NCAA could rule that Todd Mayo received preferential treatment if it's proved that he received gifts from Guillory. It was unclear how his high school eligibility or college recruitment could be affected by such a ruling.

ESPN.com reporter Andy Katz contributed to this report. Kelly Naqi is a reporter for ESPN's "Outside the Lines."