Four private lawsuits were filed by one person – a former spokeswoman for UN Secretary General Ban Ki Moon, Michele Montas. She sued the ex-dictator for "arbitrary detention, exile, destruction of private property, torture and moral violation of civil and political rights".

Madame Montas also filed the criminal complaints for "Crimes Against Humanity" with the Government Prosecutor, while other private suits were also filed by three other Haitians jailed during Duvalier's rule.

International human rights organizations Amnesty International and Human Rights Watch are strongly backing the calls for Duvalier to be charged for crimes against humanity.

"The widespread and systematic human rights violations committed in Haiti during Duvalier's rule amount to crimes against humanity," Amnesty said in a statement after his arrest.

"This landmark arrest is a welcome first step towards bringing to justice a leader whose security apparatus carried out widespread and systematic human rights violations including torture, arbitrary detentions and enforced disappearances," said Javier Zu?iga, special advisor at Amnesty International.

"Haiti must investigate Jean-Claude Duvalier, and anyone else allegedly responsible for such crimes, some of which amount to crimes against humanity, in a trial that is thorough, independent and fair.

"A cycle of impunity has prevailed for decades in Haiti, with victims of abuses and their families denied justice for way too long – now the opportunity has come for justice, truth and reparations," said Zu?iga.

"Duvalier's return should be for one purpose only: to face justice," said Human Rights Watch in a separate statement, adding that "his time to be accountable is long overdue."

But, citing manifested historical weaknesses in the Haitian legal system – such as indications by Haitian Police Chief, Mario Andressol, that charges against Duvalier have expired – the international groups, and especially US-based former victims still bearing scars of torture, are pressing for Duvalier to be tried for "crimes against humanity" under international law.

The Duvaliers' list of sins against Haiti and crimes against humanity is 29 years long.

Activists say it is impossible to say exactly how many thousands were killed altogether under "Baby Doc" and his dad, the feared Francois "Papa Doc" Duvalier, who ruled with two iron fists from 1957 until his death in 1971.

Both Duvaliers enforced terror through the feared Tonton Macoutes death squad, blamed for deaths and disposal of thousands during the Duvalier Dynasty.

Estimates of deaths in Haiti under the combined 29-year reign of the two Duvaliers range from 20,000 to 60,000 – with the disagreements only as to whether more were killed under the father dictator or his playboy son.

International human rights campaigners and victims worldwide are hoping that the start of the legal and judicial process in Haiti will accelerate and that the ex-dictator is eventually taken before an international court to answer for his and his regime's crimes against Haiti and humanity.