Mr Tessema was a high-ranking government official in Ethiopia before defecting and moving to Melbourne in 2011, where he claimed asylum.
But he faces forcible deportation in as little as two weeks, after an administrative bungle meant his appeal to the Refugee Review Tribunal was not sent.
Asked what would happen if he returned, Mr Tessema's voice shook: ''The minister has to listen. I will be tortured. I will be killed.''
Mr Tessema went to the Asylum Seeker Resource Centre to get pro bono help with his case after the Department of Immigration determined he was not a refugee.
A volunteer at the centre sent a fax of Mr Tessema's appeal application to the tribunal but misread the fax transmission report, which stated the line had been busy.
Instead, the volunteer believed the fax was successfully sent.
Staff only realised the mistake when the time limit for appeal to the tribunal had passed and Mr Tessema was told he had missed his chance to appeal to the tribunal.
About three-quarters of appeals to the tribunal have succeeded in the past year.
Asylum Seeker Resource Centre chief executive Kon Karapanagiotidis said staff at the centre, which has represented about 10,000 asylum seekers over 11 years, were ''devastated'' by the error.
In 11 years, the mistake has been made just once before. Then, former immigration minister Chris Evans intervened in the case and referred it to the tribunal for review.
''In terms of what's happened, this has caused all of us great distress and anguish,'' Mr Karapanagiotidis said.
''It's totally unfair that he's in this situation. The minister could intervene in this … that a man could find his own liberty at stake over an administrative error is completely unjust. When the error doesn't lie with him, why should he be punished for something that's out of his control?
''What should win the day? An administrative error or the fact that this man is a refugee and his life is in danger?''
Melbourne's Ethiopian community has rallied behind Mr Tessema, with almost 400 people signing a letter imploring Immigration Minister Brendan O'Connor to give him access to the tribunal. About 15 people delivered the letter to Mr O'Connor's Caroline Springs electorate office this week.
Ethiopian community leader Haileluel Gebre-selassie said he did not seek special treatment for Mr Tessema.
''However, the community believe that he should be treated like any asylum seeker, so that he can go through the existing system including the Refugee Review Tribunal, court and ministerial review before he receives his final decision.''
Mr O'Connor's spokeswoman said it was inappropriate for him to comment on a case in which he may be called to intervene.
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