WASHINGTON—Former dictator Jean-Claude “Baby Doc” Duvalier has returned to Haiti after 25 years in exile in France. By all indications, Duvalier has done so with assurances of protection from President Rene Preval, who finds himself involved in a bitter dispute over accusations that an electoral fraud in the first round of the November elections favored his son-in-law.

As if that godforsaken nation did not have enough problems already. A year after the earthquake that killed 300,000 people, one-tenth of the population still lives in tents. Less than 30 percent of the aid money promised to Haiti has arrived. Hardly any of the buildings have been reconstructed and only a small part of the rubble has been removed. A cholera epidemic has taken nearly 4,000 lives. The second round of elections has been postponed indefinitely while the dispute over the first round remains unresolved.

The last thing Haiti needed was a butcher responsible for countless political killings committed by the Tonton Macoutes—a militia originally set up by Baby Doc’s father, Francois “Papa Doc” Duvalier—and for massive corruption, to suddenly land in Port-au-Prince with a diplomatic passport and declare “I am here to help.”

The Duvalier dynasty, which governed Haiti for three decades, symbolizes, together with the Dominican Republic’s Rafael Trujillo, the era of the deranged Latin American strongman who turned his country into a fiefdom and indulged every possible perversion using his people as guinea pigs. The brutal kleptocracy that the Duvaliers imposed on Haiti is one of the reasons that republic, whose founders defeated Napoleon well before the Duke of Wellington and which used to be prosperous, is the hemisphere’s perpetual sick man.

Preval is well aware of all this. During his first term as president, in the second half of the 1990s, he made it clear that Duvalier, who had toyed with the idea of returning, would be arrested and face trial if he did. Even as recently as 2007, when Duvalier broadcast a radio address to the nation, Preval said the situation had not changed. And on Tuesday, Duvalier was taken before a judge in Port-au-Prince, but it was not clear if he would face charges.

Despite the confusion Tuesday, why was Duvalier allowed to go through immigration and customs with a diplomatic passport, greet supporters, check into a hotel, meet with advisers and then prepare a news conference? His return could not have been a surprise since the French government had reportedly known that Duvalier was planning his trip and justified its own permissiveness with the argument that the exiled tyrant was free to travel.

Preval is playing a sinister game. His conduct since the earthquake has been that of a man hell-bent on remaining in power vicariously. He made no secret of his support for Jude Celestin, his son-in-law who ran for president in the November elections, while evidence surfaced that his influence on the electoral body was unhealthy. Then, when it became clear that the election was rigged to facilitate Celestin’s advance to the second round against Mirlande Manigat, who polled first, Preval doubled down. Even when the Organization of American States, after a long investigation, handed him a document officially stating that Manigat’s rival in the runoff should be Michel Martelly, the popular singer who has revolutionized Haitian politics, Preval refused to back down.

What an extraordinary transformation this is. Preval was a democratic president in the 1990s who handed power over to his successor and who, while implementing not unreasonable economic policies, was in favor of prosecuting military and police officers accused of human rights violations. Now, finding himself the target of accusations of corruption and abuse of power, in the midst of a veritable inferno following last year’s catastrophe, he has decided to bring into a country the symbol of everything that was wrong in the 20th century, dashing hopes that Haitians will find peace and stability.

Something tells me, especially if Duvalier seeks a return to power, that we have yet to see the worst. I admit I would not be entirely surprised if in the midst of the suffering and hopelessness a significant number of Haitians suddenly began to look at Duvalier with something more than mere curiosity, in the case of those too young to remember, or less than revulsion in the case of those who grew up hearing the dark stories.