JUBA (Reuters) - A South Sudanese army commander on trial for his role in an attack on aid workers has been found dead in military custody, an army spokesman said on Friday. The attack by soldiers at the Terrain Hotel in the capital Juba was one of the worst on aid workers since South Sudan plunged into civil war in 2013.  The rape of five foreigners and murder of their local colleague occurred on July 11, 2016 as President Salva Kiir s troops won a three-day battle in Juba over opposition forces loyal to ex-Vice President Riek Machar.  Lt. Col. Luka Akechak was found dead last weekend, army spokesman Santo Domic Chol told Reuters on Friday. Chol said Akechak had fallen sick  some weeks ago  and received medical treatment in Juba but did not recover.  The military custody told us that the man was found dead in the morning.  Akechak was the unit commander at the hotel on the day of the attack and is one of more than a dozen South Sudanese soldiers standing trial in a military court.  The army spokesman said that in the last hearing, one of the rape survivors who testified said she witnessed Akechak directing the soldiers to raid property at the hotel.   The next hearing in the trial is scheduled for Wednesday.  Lawyer Philip Manyang, who is representing survivors of the attack in court, told Reuters that survivors would be testifying by video conference in a closed session. 