A copy of President Abraham Lincoln’s 1863 Emancipation Proclamation to end slavery that was owned by Robert F. Kennedy will be auctioned in December, Sotheby’s said yesterday.

The document, signed by Lincoln and one of only 19 copies known to still exist, is expected to sell for between $1 million and $1.5 million dollars, the auction house said.

Kennedy was U.S. attorney when he bought the copy of the Emancipation Proclamation in 1964. It has been kept since at the Hickory Hill residence in McLean, Va., that he shared with his wife, Ethel.

The Kennedy Emancipation Proclamation will be exhibited to the public in Boston, Philadelphia and New York ahead of the Dec. 10 auction.