GENEVA, June 18 (Reuters) - A Swiss court will rule on Friday whether a Liberian rebel commander committed rape, killings and an act of cannibalism in one of the only civil war-era cases from the West African country to ever go to trial. The case is also Switzerland"s first war crimes trial in a civilian court. It involves the 46-year-old Alieu Kosiah who went by the nom de guerre "bluff boy" in the rebel faction ULIMO that fought former President Charles Taylor"s army in the 1990s. "For both Liberia and Switzerland this is a very big day," said Alain Werner, a Swiss lawyer at NGO Civitas Maxima which filed the complaint on behalf of victims. "This case is definitely raising questions about impunity in Liberia." Liberia has ignored pressure to prosecute crimes from its back-to-back wars between 1989-2003, in which thousands of child soldiers became bound up in the savagery. Taylor was sentenced for war crimes in 2012, but only for acts in neighbouring Sierra Leone. His son, Chuckie, was sentenced for torture in Liberia by a U.S. court in 2009. Kosiah was arrested in 2014 in Switzerland, where he had been living as a permanent resident. A 2011 Swiss law allows prosecution for serious crimes committed anywhere, under the principle of universal jurisdiction. The three-judge panel at the Federal Criminal Court in Bellinzona will rule on 25 counts, including recruiting a child soldier and joining fighters in eating slices of a victim"s heart. Kosiah denies the charges, saying he was not there at the time the acts were committed. Around 15 Liberians testified during the trial. Emotions were sometimes intense, with Kosiah disrupting proceedings repeatedly on the opening day to cry out against his six-year pre-trial detention. One of the plaintiffs, who says Kosiah ordered his brother"s murder, began shaking during his testimony and asked to be seated further away from the defendant, witnesses said. Kosiah, who says he was a minor when first recruited into the conflict, faces a sentence of up to 20 years. Liberia"s Truth and Reconciliation Committee recommended the creation of an extraordinary court but proceedings never began there and some former warlords now occupy positions of power.