The fraudster, one Lew Bloom, apparently had enough painting skills to modify an existing portrait of an unknown woman to resemble the First Lady. He then invented a chain of ownership dating back to Francis Bicknell Carpenter, a painter who lived at the White House for a time in 1864 while he painted "First Reading of the Emancipation Proclamation of President Lincoln."
Carpenter did not, however, paint the First Lady, as a conservator recently discovered when cleaning the painting. Lew Bloom apparently sold the fake to Jessie Lincoln, the president's granddaughter, for $2,000 or $3,000 -- a great deal of money at the time -- and Lincoln's great-grandson, Robert Todd Lincoln Beckwith, ultimately gave the portrait to the Illinois State Historical Library in 1976.
In the late 1980s, the painting was sent to the governor's mansion. Now that it's known to be a fake, the Abraham Lincoln Presidential Library and Museum will keep the painting. It might not be the artifact it was thought to be, but it still has an interesting Lincoln-inspired back story.