Cops say they're not sure why anybody would steal a plaster cast of one of President Abraham Lincoln's hands from an Illinois museum, but more than three weeks later, they still need clues to crack the case.

The stolen hand is roughly the size of an "8-10 pound ham," a curator at the Kankakee County Museum told police. Historians say the sculptor, George Grey Barnard, lived in Kankakee around the time the 16th president was assassinated in 1865.

Police have struggled to find leads since the hand vanished sometime around Dec. 11, The New York Times reported.

The hand is over 150 years old, police say. Kankakee is about 60 miles southwest of Chicago.

The Kankakee Police Department urged anybody with information to call its investigations bureau. And an editorial in the Kankakee Valley Daily Journal urged the culprit or culprits to "hand the Lincoln sculpture back over."

According to the editorial, "While the sculpture has great historical and sentimental value, it is relatively worthless to the average person. Unlike stolen copper, it won't command much of a price from a recycler, and only a serious art collector would pay significant money for it."