Forward Alex Poythress told CBSSports.com that Krzyzewski spoke to him earlier this week while he was in Orlando, Fla., for a tournament with his AAU team, the Georgia Stars, and offered him a scholarship. Poythress and the Stars recently competed in the Nike Peach Jam in North Augusta.
NCAA rules prevent coaches from contacting recruits before they are finished playing in tournaments.
Duke spokesman Jon Jackson said in a statement Saturday that the school is gathering facts and that "proper adherence to NCAA bylaws has always been, and will continue to be, a cornerstone of Duke Athletics."
Poythress is a 6-foot-7 forward from Clarksville, Tenn. He is considered one of the nation's top high school seniors.