By Tsegaye Tadesse ADDIS ABABA, Dec 6 (Reuters) - The long-awaited verdict in Ethiopia's more than decade-old genocide trial of former Marxist ruler Mengistu Haile Mariam will be issued next week, officials said on Wednesday. Mengistu, who has lived in exile in Zimbabwe since 1991, has been tried in absentia with 73 other officials accused of involvement in killing tens of thousands of people during his 17-year-rule, including the 1977-78 "Red Terror" campaign. The verdict was to be delivered in May but was postponed after the court said it needed more time to assess evidence. "The time set to give the final verdict on the trail of Colonel Mengistu Haile Mariam and his officials was brought forward to Dec. 12 from Jan. 23," a statement from Ethiopia's office of the special prosecutor said. Mengistu's rule began with the toppling of Emperor Haile Selassie in 1974 and included war, brutal purges and famine. During the "Red Terror", suspected opponents were rounded up, then executed by garrotting or shooting, their bodies often thrown into the streets. Zimbabwe's President Robert Mugabe has failed to respond to a request to extradite Mengistu, the prosecutor's office said. Of his 73 former officials on trial, about 40 are in jail while 27 are being tried in absentia. A few have died. The most prominent victim Mengistu is accused of killing was Haile Selassie, said to have been strangled in bed and secretly buried under a latrine in his palace. According to charges by the prosecutors, the former officials also killed more than 1,000 people, which included the execution of 60 ministers, top officials and members of the royal family by firing squad.Witnesses said family members who went to morgues to collect bodies of their loved ones were asked to pay for bullets that killed them.Human rights groups have expressed concern at the amount of time the trial has taken, but the prosecution says the complex nature of the evidence is what had delayed the verdict.