Abuja - Several high-profile Nigerians are facing charges as part of a drive against corruption but there are concerns the government is settling old political scores and flouting due process.
President Muhammadu Buhari has vowed to recoup what he said were "mind-boggling" sums of public money stolen under previous administrations to fulfil a campaign pledge to end graft.
This week, the government claimed just 55 people stole more than $6 billion between 2006 and 2013, leaving Nigeria in the lurch as its economy struggles due to the global oil price slump.
But it is former national security advisor Sambo Dasuki who has become the key figure in the anti-corruption campaign.
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The former army colonel is accused of looting billions of dollars that were aimed at buying weapons and equipment for troops fighting Boko Haram Islamists.
Cash is alleged to have been diverted instead to members of former president Goodluck Jonathan's Peoples Democratic Party (PDP) to fund his failed re-election campaign.
Dasuki was granted bail last month but has been kept in custody without access to his legal counsel as he awaits the start of three trials, his lawyer Joseph Daudu told a court in Abuja on Wednesday.
Dauda said the detention was a "brazen affront" to the judiciary and the judge agreed.
"I don't see how I can be conducting a criminal trial without the presence of the accused person," said judge Adeniyi Ademola. "You can set a dangerous precedent as it is."
Dauda later claimed Buhari was reverting to his old autocratic habits from his days as military ruler in the 1980s.
"He (Buhari) emphasised he was a changed man, open to democratic principals. But interfering with the court system, trying to find your own rule of law, is not good," he told AFP at his office.
"It makes the outcome suspect."
Prosecutor Oladipo Okpeseyi, however, denied any impropriety. "The federal government has obeyed every order made in respect of this case. We are not acting illegally in any way whatsoever," he said.
But Buhari's own comments about Dasuki and two other cases involving the pro-Biafra activist Nnamdi Kanu and the Shiite Muslim leader Ibrahim Zakzaky have rung alarm bells.
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He told reporters in December the men should be kept in custody because they had committed "atrocities" against the government -- despite none of them having been tried and convicted.
Kanu was arrested in October. He was granted bail in December but remains in secret police custody, pending a trial on "treasonable felony" charges.
Zakzaky was detained after a military raid on the headquarters of his Islamic Movement of Nigeria that it is claimed left hundreds dead. It is not clear whether he has been charged with any offence.
'Nothing to fear'?
Buhari was voted into power in 2015 after vowing to stamp out corruption and usher in a new democratic era free from bitter partisanship.
He won over sceptics by preaching forgiveness and pledged an impartial war on graft in the interest of political harmony.
"President Jonathan has nothing to fear from me," Buhari said in his acceptance speech last April. "Let's put the past behind us, especially the recent past."
But with the prosecution of Dasuki - a powerful member of Jonathan's administration -- the former head of state could yet be dragged into the case.
"The national security advisor will normally carry out the instructions of his president," Dasuki's other lawyer Ahmed Raji told AFP.
"You cannot talk about this matter without talking about President Jonathan."
Buhari's anti-corruption zeal has been widely praised and seen as much-needed but political analyst Chris Ngwodo said "it just has to be conducted in the right way".
"Corruption will be beaten by straightening institutions, not by disregarding them," he added.
The Economic and Financial Crimes Commission (EFCC) is casting an ever-widening net to bag corrupt officials in Africa's most populous nation and leading economy.
But few charged with siphoning public funds have had their day in court and with most accused or subject to investigations being PDP members, the party has accused Buhari of conducting a witch-hunt.
Prominent PDP supporter and media magnate Raymond Dokpesi has been charged in the Dasuki case along with the party's spokesman Olisa Metuh. who appeared in court recently in handcuffs.
That so many PDP figures have been arrested risks stoking tensions in a country where partisan loyalty frequently erupts into deadly violence.
"Securing actual convictions of these people, that is the real litmus test of the anti-corruption campaign," Ngwodo said.