Dubbed the Truth, Reconciliation and Reparations Commission (TRRC), the panel faces high expectations of justice in this struggling young democracy.
But it is far from clear whether the man at the centre of it all will ever be put in the dock.
“Prosecuting perpetrators is a lesson to others that no amount of time or distance or power can prevent justice,” human rights activist Madi Jobarteh told AFP.
For 22 years, Jammeh was kept in place by a web of oppression that touched nearly every part of Gambian society.
Death squads, disappearances, sexual violence, torture and summary detention were its hallmarks.
Need to heal
The nightmare – but not the memories – ended only when Jammeh was forced out in January 2017 after he stunningly lost elections to opposition leader Adama Barrow.
He flew into self-imposed exile in Equatorial Guinea after regional countries intervened diplomatically and militarily.
Despite taking the helm of one of the world’s poorest countries, Barrow has earned much praise for sweeping away Jammeh’s structure of oppression.
But healing the wounds largely lies with the TRCC, a project inspired by the South Africa’s famous post-apartheid Truth and Reconciliation Commission.
Created under an act of parliament, it aims at using openness and a court-like approach to investigate how abuse began and became systemic and the impacts it had.
Victims and witnesses will be invited to testify in public hearings, with specific sessions on certain themes or the role of institutions.
The commission will be empowered to recommend financial compensation and advise prosecution of perpetrators.
Eleven commissioners, drawn from all the major regions, its five main ethnic groups and two religions, will be sworn in on Monday.
The panel, led by a retired UN diplomat, Lamin Sise, notably includes four women, one of whom is deputy chair. Gender-based violence is expected to be a major theme of the two-year mission.
Hundreds of cases
The Center for Victims of Human Rights Violations, an NGO set up by victims and relatives of victims, says it has already documented hundreds of cases, although the full extent of abuse may never be known.
Political dissidents and the media were especially targeted.
One such victim was the BBC’s former correspondent in Banjul, Lamin Cham, who was picked up in June 2006 and tortured by Jammeh’s personal bodyguards at the headquarters of the dreaded National Intelligence Agency (NIA).
“I was asked why I chose to report for a particular foreign media organisation, and why I mentioned Yaya Jammeh’s name on my reports,” Cham told AFP.
Senior members of the NIA are already on trial in a major case, and some members of Jammeh’s ultra-loyal death squad, known as the “Junglers” are behind bars.
In South Africa, the trail-blazing Truth and Reconciliation Commission began its work after an orderly, negotiated end to apartheid and democratic elections.
But the TRRC does not enjoy the advantages of political closure.
It must juggle the anger of victims with the resentment of Jammeh supporters and the absence of the former autocrat himself.
The tense mood is reflected by brawls outside the trial which began last year of nine NIA officials, including its director general and deputy director general, accused of torturing to death a political activist, Solo Sandeng, in 2016.
Marta Colomer of Amnesty International said the TRRC’s immediate task was to ensure “people from all over the country fully understand its mandate and missions.”
“This will be key to managing the victims’ expectations,” she told AFP.
“They suffered terrible human rights violations for many years and some of them have really high expectations of what the TRRC will be doing for them.”
The TRRC’s work will unfold even as Jammeh continues to cast his shadow over the country.
In July, the country was shocked by a leaked 10-minute audio recording between Jammeh and a senior figure of the former ruling party, the Alliance for Patriotic Reorientation and Construction (APRC).
It was the first time, Jammeh’s voice had been heard since he went into self-imposed exile.
In it, Jammeh, 53, was heard laughing and cracking jokes.
“I… once told Gambians that they will not know who I am until I leave that country,” he said, in remarks that some feared were a hint of a comeback.