SPRINGFIELD (AP) — A famous portrait of Abraham Lincoln's wife that hung in the Illinois governor's mansion in Springfield for more than three decades — along with the presidential folklore that followed it — is a fake, officials said.

Abraham Lincoln Presidential Library and Museum curator James Cornelius said Saturday that the painting of Mary Todd Lincoln and its famous backstory appear to be a fraud, discovered when the painting was recently sent for a cleaning and an art restorer noted that the signature and other details on the painting appeared to have been added later.

According to Illinois folklore, Mary Todd Lincoln had Francis Carpenter secretly paint her portrait as a surprise for the 16th president, but Lincoln was assassinated before she had a chance to give it to him.

Instead, it appears that the painting — which officials now say depicts an anonymous woman and was painted by an anonymous painter — was altered by another painter who then invented the story about Mary Todd Lincoln, one that has been repeated for decades.

"It doesn't have the backstory we thought it had, but in a way it has new backstory that's quite intriguing," Cornelius told The Chicago Tribune.

Barry Bauman, the art restorer, said a painter appears to have altered the subject's facial features, painted over some accessories, including a necklace with a cross, and added a brooch with the president's picture. He will present his findings at the Springfield museum on April 26. The painting will then be on display at the museum.

Cornelius said the painting was sold to the Lincoln family in the late 1920s for between $2,000 and $3,000. It stayed in the family's possession until it was donated to the state historical library in 1976.

Sunday marked Abraham Lincoln's 203rd birthday.