Although Duvalier had previously been threatened with arrest if he returned, President Preval has more recently said he would be allowed to come back. There appeared to be no threat of arrest Sunday, although it remains unknown if Preval even knew Duvalier had planned to return.
When Duvalier was exiled to France in 1986, Haitians celebrated the boy-tyrant's overthrow and the end of a bloody, terror-filled regime that began under his late father, Francois "Papa Doc" Duvalier in 1957.
Amnesty International criticized the Haitian government for allowing Duvalier to return without facing prosecution.
"The widespread and systematic human rights violations committed in Haiti during Duvalier's rule amount to crimes against humanity," the group said. "Haiti is under the obligation to prosecute him and anyone else responsible for such crimes."
ABC News Matt Gutman contributed to this report.