Sani Abacha's rule: 'worst period in Nigeria's history'
Some Nigerians have been urging a commission investigating past human rights abuses to take a stronger stand against former military rulers.
The Human Rights Violations Investigations Commission was set up by Nigerian President Olesegun Obasanjo in 1999, with a mandate to look back over a period of more than 30 years.
Described by one Nigerian newspaper as the greatest show on earth, the commission is meant to help Nigeria come to terms with its past, looking at the most shameful episodes in the country's history and making the main protagonists accountable for their actions.
Amongst the prominent Nigerians to appear before the Commission in Abuja recently has been Nobel Laureate Wole Soyinka.
He documented the long campaign of harassment against him, organised by the late military ruler Sani Abacha.
The Abacha government is seen by many Nigerians as the worst period in Nigeria's history, a time of crude military dictatorship and flagrant human rights abuses, the price of which was international condemnation and isolation.
Declined to appear
But while Sani Abacha is not alive to face his detractors, other military rulers are - for example Ibrahim Babangida, who ruled Nigeria for eight years before presiding over a botched transition to democracy in 1993.
Mr Babangida has so far declined to appear before the Commission and President Obasanjo has signalled that there is no need for him to give evidence.
Also considered unlikely to appear in Abuja or anywhere else, is Abdulsalami Abubakar, who succeeded Mr Abacha in June 1998.
Mr Abubakar was widely praised, particularly abroad, for opening Nigeria up and allowing political normality to return, but his critics say Mr Abubakar too has much to account for.
In his recent testimony in Abuja the writer Mr Soyinka said the Abubakar regime had sanctioned the murder of opposition politician Moshood Abiola in prison in 1998.
Mr Abiola collapsed while being visited by a high level American delegation.
His death was reported at the time as being due to natural causes.