Rogerio Da Costa is being deported today, a week after he arrived in Britain to meet his family for the first time.
His aunt, Ros Clapperton, of Hove, is making a last- ditch attempt to stop her nephew being sent back to Brazil at 6pm today.
Rogerio, 24, wanted to see where his mother, Elizabeth, lived before she died.
But within minutes of his arrival at Heathrow, airport immigration officials took him away to be questioned for almost nine hours.
His 57-year-old aunt, from Grange Road, Hove, said she was not allowed to see him while officers quizzed him about why he had come to the UK.
Now Rogerio, who speaks hardly any English, has only a few hours left before he is deported to Portugal en route for southern Brazil, where he lives.
Ros said: "He had travelled thousands of miles to get here and to meet all of us. He was in a terrible state when I eventually got to him.
"He was very distressed and I was crying too. We thought it would be a lovely moment to meet at last after all this time. But instead it has been a nightmare."
Rogerio, who is a business studies student in Brazil, had planned to stay with his aunt in Hove before meeting other relations including another aunt in Scotland before returning home in March.
Ros said he wanted to see the country where his mother, who died in August last year from lung disease and other related illnesses, grew up before her family moved to Brazil.
She has contacted a friend who is a solicitor to see if the deportation order can be overturned.
She said: "The authorities were suspicious it seems because mine and his stories were so different. But his English is so poor he didn't understand. He just agreed to anything and didn't know what was going on."
Immigration officers at Heathrow confiscated Rogerio's passport when he arrived last Thursday.
He was handed official papers which stated: "You have asked for leave to enter the UK for up to three months as a visitor, but I am not satisfied that you are genuinely seeking entry as a visitor for the limited period as stated by you."
Ros says they wanted to send him home straight away, but finally agreed to let him stay for just one week.
A spokesman for the Immigration Office said: "We cannot comment on individual cases, but if his passport has been stamped saying he must return, I'm sure there is a good reason for that."
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