The NBA has closed its investigation into Josh Giddey, sources told ESPN's Adrian Wojnarowski on Thursday, after police previously determined they would not pursue charges following allegations that the Oklahoma City Thunder guard had an inappropriate relationship with an underage girl.

Newport Beach (Calif.) police announced in January that they had been "unable to corroborate any criminal activity" by Giddey and would not pursue charges.

The NBA came to a similar conclusion and closed its investigation, sources told Wojnarowski.

The allegations against Giddey surfaced on social media in late November. In a since-deleted post, an anonymous social media user said a girl who is seen with Giddey in videos and photographs was a high school junior at the time. The social media account was deactivated since making the post.

Newport Beach police opened an investigation on Nov. 29, and NBA commissioner Adam Silver had said in early December that the league's investigation would "take a back seat" to the police's process.

Giddey, 21, has declined to comment about the allegations. He continued to play for the Thunder through their run to the Western Conference semifinals, averaging 8.7 points and 3.6 rebounds per game in the playoffs.

Information from ESPN's Tim MacMahon was used in this report.