Authorities searched Andersen's Larkspur, Colo., home Thursday morning and seized property. Andersen, 33, has not been arrested or charged with a crime.
"The Denver Nuggets are aware of media reports involving Chris Andersen. It involves a legal investigation and we await further details," team officials wrote.
The team declined further comment, as did Andersen, who has not played in the team's playoff series against the L.A. Lakers, which is now died at 3-3.
Douglas County Sheriff's Office spokeswoman Deborah Sherman said the investigation is open but would not speak on the allegations against Andersen.
"It could include many different things. Right now we're not saying. They literally just got the property this morning," Sherman told reporters Thursday.
The spokesman went on to add, "The Sheriff's Office did contact Mr. Andersen this morning while he was at his house, and he cooperated fully."
With his colorful tattoos, hustle on the court and charitable endeavors, the reserve player has been a fan favorite in Denver area for years now.
Mark Bryant, Andersen's lawyer and confidant, released a statement to The Denver Post calling him an "outstanding member of this community."
"I believe in Chris. I would ask the citizens of Colorado to give Chris his due," Bryant wrote. "Like every one of us, he is presumed innocent. At the end of the day, I am confident it will be shown that he did nothing wrong."
In Colorado, Internet crimes against children can include exchanging pornographic images of kids to using chat rooms to lure children for sexual purposes.
Frequently in these types of investigations, police seize computers, data-storage devices and other electronics. It is unclear if that happened here.
Proving who used a seized device can be tricky if multiple people had access to it. Reports say - a 30-year-old woman - may live at the Larkspur home.
Andersen has been under investigation since February, when a California law enforcement agency tipped off Douglas County investigators.