MUSKEGON, Mich. (AP) — A white police officer in western Michigan is on paid administrative leave after an apparent Ku Klux Klan document was seen framed on a wall of his home.

The Muskegon Police Department opened an internal investigation after Robert Mathis, who is black, posted on Facebook that he saw the document while touring the officer’s Holton-area home, which was for sale. He said he also saw Confederate flags at the house.

City Manager Frank Peterson said Thursday that Officer Charles Anderson, who has been on the force more than 20 years, is on leave indefinitely.

Anderson told MLive.com he was advised not to comment amid the investigation. Rachael Anderson told WOOD-TV her husband isn’t a Klan member and if he could comment “it would probably set a lot of things straight.”