(CNN) The staff at an Idaho public library spends most days helping patrons find books they need. But lately, librarians have had to become amateur sleuths -- because someone keeps hiding books to prevent others from reading them.

Many of the titles that have gone missing in Coeur d'Alene are critical of President Donald Trump. And books on LGBTQ issues, human rights, immigration and women's suffrage have been squirreled away in the 38,000 square foot building, library director Bette Ammon said.

Ammon said about 20 books have disappeared, some more than once.

"A gun rights book, we just found it last week behind the O's in the fiction [section] on the bottom shelf behind a bunch of books," Ammon told CNN.

She added that the fiction section is in an out-of-the-way corner.

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