Mr Sonko faces charges of murder, rape, false imprisonment, torture, among others.
Ousman Sonko, a 54-year-old former interior minister of the Gambia, goes on trial for crimes against humanity in the Swiss Federal Criminal Court in the city of Bellinzona Monday.
This is for his alleged role in a series of crimes perpetrated against Gambians under the 22-year rule of small country's former dictator Yahya Jammeh.
Mr Jammeh ruled Gambia with an iron fist and was accused of numerous human rights violations including murder and severe torture by the country's Truth, Reconciliation and Reconciliation Commission.
Mr Sonko first served in the military, rising through the ranks to command the State Guards, an elite military unit which guards the Gambian presidency, in 2003.
Mr Sonko would serve both as the head of the Gambia police and the interior minister presiding over the internal security matters of the country from 2005 to 2016.
In 2016, Mr Sonko fell out with Mr Jammeh and fled to Switzerland.
He was arrested in Bern in January 2017, a day after the Geneva-based rights organisation-- Trial International-- filed a criminal complaint against him. He was formally indicted by the Swiss Office of the Attorney General before the Federal Criminal Court in April 2023.
Mr Sonko faces charges of murder, rape, false imprisonment, torture, among others. Nine Gambian victims are bringing the case against him in the three-week trial which ends by 30 January. A tenth plaintiff passed away in October allegedly as a result of lasting injuries inflicted by Mr Sonko.
The Swiss Office of the Attorney General also accuses Mr Sonko of having co-perpetrated deprivation of liberty and acts of torture of peaceful demonstrators in 2016, when he was Minister of the Interior. These acts have been qualified by the Swiss prosecutor as crimes against humanity.
"This trial is a significant moment in Swiss judicial history," said Leslie Haskell, president of TRIAL International.
Mr Sonko is the second person to face trial in Switzerland under the principle of universal jurisdiction which holds that crimes against humanity are committed against all humans regardless of where they were committed.
The first person to face trial in Switzerland under universal jurisidiction, Alieu Kosiah of Liberia, was convicted and sentenced to 20 years prison in 2022.
"Ousman Sonko will also be the highest-ranking state official ever to be tried for international crimes under the principle of universal jurisdiction in Europe."
According to the indictment, Mr Sonko participated in the murder of Almamo Manneh in January 2000. Mr Manneh was a former member of the elite guards of the Gambian presidency, State Guards, who was accused of being part of a coup.
After murdering Mr Manneh, Mr Sonko allegedly raped Mr Manneh's wife dozens of times- an abuse which persisted over five years. Jamba first narrated her story before the country's Truth Commission in October 2019.
The Commission finalised its reports and submitted them to the Gambian president in November 2021. In 2022, the government published a white paper accepting the recommendations of the Commission. Mr Sonko is named on the list of the 90 most adversely mentioned individuals published in July 2022.
The Commission found Mr Sonko to be involved in a scheme to cover up the killing of at least 51 West African migrants in the country in 2005.
The migrants who hailed from at least four West African countries-- Ghana, Nigeria, Senegal and Togo-- were accused of being mercenaries and handed to members of Mr Jammeh's hitsquad to be shot at point blank, the Commission's investigation found.
Mr Sonko is accused of participating in the murder of a former ally of Yahya Jammeh, Baba Jobe. Mr Jobe was killed on his hospital bed at the country's main referral hospital in Banjul in October 2011.
Mr Sonko also faced allegations of participating in the torture of several civilian and military officers accused of plotting to overthrow Mr Jammeh's regime in 2006.
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Mr Sonko is also accused of participating in the torture of opposition political activists in April 2016. A rare protest broke in the Gambia led by political activists and members of the opposition UDP. The protesters, led by Ebrima Sandeng, were rounded up and tortured.
Mr Sandeng would die in state custody. At least five 'victims of torture' in that incident have since died, and one of them-- Nogoi Njie-- was expected to testify against Mr Sonko in Switzerland.
Mr Sonko is the second member of Mr Jammeh's regime to face trial. In November, Bai L. a former member of a paramilitary unit known as "Junglers" created by the former President, was sentenced by a German court to life imprisonment for crimes against humanity.
Michael Correa, another alleged member of the same death squad, will stand trial in Denver, USA, in September. He faces charges of torture and conspiracy to commit torture.
A verdict in Mr Sonko's trial is expected later in the year.
This story was a collaboration with New Narratives as part of the West Africa Justice Reporting Project.
