Boston Police are investigating two works of art missing from the Boston Public Library.

The BPD Ant-Corruption Unit is looking into the disappearance of a Rembrandt etching valued between $20,000 and $30,000 and an Albrecht Dürer engraving of Adam and Eve worth more than $600,000 according to The Boston Globe. 

Staffers noticed the works were missing on April 8 and notified the police.

But, library president Amy Ryan told the Globe,”It is our hope that these two significant pieces have simply been misfiled.”