Belgium has arrested a high-ranking member of the rebel movement that plunged Liberia into conflict more than two decades ago and charged her with war crimes and crimes against humanity, a spokesman for federal prosecutors said Thursday.

The charges against Martina Johnson, former head of the heavy artillery unit for the National Patriotic Front of Liberia, are believed to be the first against a Liberian for international crimes committed during the country’s first civil war.

Johnson has been described as a leader of Operation Octopus, a brutal battle for Liberia’s capital city, Monrovia, in 1992 that killed thousands and saw extensive rapes and looting by the NPFL’s Small Boys Unit.

Liberian victims filed a complaint against her in 2012 in Belgium that focused heavily on Operation Octopus.

Johnson was arrested in Belgium this week, said Jean-Pascal Thoreau, the Belgian prosecutors’ spokesman. She is scheduled to appear Friday before a judge who will decide whether to hold her in continuous detention or set her free, Thoreau said.

Led by Charles Taylor, the NPFL launched its assault on Liberia in December 1989. Tens of thousands of people were killed before the civil war ended in 1996, the year before Taylor became president.

A second, four-year civil war ended when Taylor stepped down and fled to Nigeria in 2003. The two wars are often said to have killed more than 250,000 people, though some scholars believe that figure is inflated.

Taylor was never tried for crimes committed in Liberia. He is serving a 50-year sentence in Britain, convicted by an international court of war crimes and crimes against humanity related to his involvement in neighboring Sierra Leone’s civil war.

His son, Chuckie Taylor, was the only Liberian besides Johnson to be charged with international crimes for Liberia’s wars. A U.S. court in 2008 found Chuckie Taylor guilty of torture committed while he headed his father’s Anti-Terrorist Unit from 1997 to 2003.

There has been no observable progress on establishing a war crimes tribunal in Liberia.

In 2009, the country’s Truth and Reconciliation Commission recommended the prosecution of more than 100 people, including Johnson.

Justice advocates say Martina Johnson’s indictment is an important step toward establishing some accountability for Liberia’s wars.

“Impunity has been almost absolute for the alleged perpetrators who committed war crimes in Liberia during the war,” said Alain Werner, director of Civitas Maxima, a Geneva-based organization that provides legal representation for victims of war crimes and crimes against humanity.

Civitas Maxima has worked since 2012 with the Global Justice and Research Project in Liberia to document war crimes during Liberia’s wars.

“The initiative came from Liberian victims who were seeking justice, and without the determination of those Liberian victims this arrest will never have taken place as nobody would have known about these crimes,” said Werner, who also worked on Charles Taylor’s prosecution.

Operation Octopus began on Oct. 15, 1992, when Taylor’s forces attacked positions of a West African peacekeeping force, ECOMOG. The assault was led by intoxicated boys and teenagers who were unpaid but were given permission to loot Monrovia, according to Human Rights Watch.

The World Health Organization later estimated that up to 3,000 civilians and fighters were killed in the operation, and HRW said 200,000 people were displaced. Officials from the interim government and five American nuns living in a Monrovia suburb were summarily executed.

Associated Press