Duke University said Saturday it was "looking into" allegations that star freshman basketball player Zion Williamson's mother was paid by Nike.

California lawyer Michael Avenatti tweeted Friday that Nike executive Carlton DeBose bribed Williamson and other five-star recruits to attend schools associated with the Nike brand.

Federal prosecutors in New York have accused Avenatti of attempting to extort Nike. Avenatti claims Williamson’s mother, Sharonda Sampson, received money from Nike during her son’s recruitment. Avenatti shared a 41-page document over social media, but it did not contain anything specific mentioning Williamson.

Kevin White, Duke’s director of athletics, said in a statement to media outlets, including USA TODAY Sports, that the university is investigating the matter and noted a thorough vetting process already took place before Williamson played for Duke.

“We are aware of the allegation and, as we would with any compliance matter, are looking into it," White wrote. "Duke is fully committed to compliance with all NCAA rules and regulations. Every student athlete at Duke is reviewed to ensure their eligibility. With regard to men’s basketball: all recruits and their families are thoroughly vetted by Duke in collaboration with the NCAA through the Eligibility Center’s amateurism certification process.”

Nike issued the following statement to USA TODAY Sports:

“Nike will not respond to the allegations of an individual facing federal charges of fraud and extortion and aid in his disgraceful attempts to distract from the athletes on the court at the height of the tournament. Nike will continue its cooperation with the government's investigation into grassroots basketball and the related extortion case.”

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Williamson, the projected No. 1 pick in the NBA draft, accepted two national player of the year awards on Friday at the Final Four -- for the Associated Press and U.S. Basketball Writers Association, and said it felt bittersweet to accept those as "team awards" but not be playing in the national semifinal game Saturday. Williamson's Blue Devils lost by one point to Michigan State in the Elite Eight to end their season.

Williamson is expected to announce which major shoe company he plans to sign with after he officially declares for June's NBA draft.

Avenatti's previous allegations included claims against former Arizona player Deandre Ayton and Oregon player Bol Bol.

In his latest social media postings, he wrote, in part: "Can you please ask Zion Williamson’s mother – Sharonda Sampson – whether she was paid by @nike for bogus “consulting services” in 2016-17 as part of a Nike bribe to get Zion to go to Duke? Thx.”

During the NCAA tournament, Duke coach Mike Krzyzewski denied to comment on Avenatti’s previous allegations when asked by news reporters.

Messages made by USA TODAY Sports to Nike were not immediately returned on Saturday. Nike has sponsored Duke athletics since 1992.