Documents seen by BBC News suggest that a man from Staffordshire, convicted of murder in Italy, was not in the country at the time.
Edmond Arapi, who lives in Leek with his wife and three young children, was given a 16-year jail term in his absence.
His lawyers claim he is the victim of mistaken identity and are urging the Italian authorities to withdraw their request to extradite him.
Legal campaigners say the case highlights flaws in the fast-track European Arrest Warrant scheme.
Mr Arapi, an Albanian chef legally resident in the UK and married to a British woman, was convicted of stabbing to death Castillo Marcello in Genoa, in northern Italy, in October 2004.
According to prosecutors, a distant relative and workmate of Mr Arapi implicated him in the murder.
The Italians allege Mr Arapi fled to Albania and from there phoned the relative, confessing to the crime.
In his absence and, says Mr Arapi, without his knowledge, he was tried, convicted and given a 19-year prison term - reduced to 16 years after an appeal which he also apparently did not know about.
Laughing 'through shock'
When the 29-year-old chef was eventually arrested at Gatwick Airport on his way back from a holiday in Albania in June 2009, he was deeply shocked.
"All of a sudden some police officers came around - three or four of them," he recalls.
"They said 'We're arresting you for a murder'. At the time I just laughed, laughed through shock.
"I said 'Is this some kind of joke? Are you filming this or something?'"
But it was no joke and there was no film.
Mr Arapi has spent the past 12 months - including several weeks in custody - battling to clear his name and avoid extradition.
He has compiled evidence to show that he was not in Italy at the time of the murder.
Witnesses say he had just started a chef's course and was working at the Cafe Davide in Leek - 780 miles away from Genoa.
An invoice for a food delivery - shown to BBC News - backs up the account.
The document records items received by Cafe Davide on October 26, 2004 - the day of the murder - and is signed by Edmond Arapi.
A handwriting expert examined the signature and concluded that it was likely to be his.
Besides, said Mr Arapi, his immigration status in 2004 meant he was not allowed to travel abroad without permission.
His legal team and supporters believe the evidence points to a case of mistaken identity.
An alias that Italian prosecutors say Mr Arapi used is said to be the same as the name of an Albanian man from the village he grew up in.
The man is on the run and is being pursued for other crimes by the Albanian authorities.
However, in March a British district judge approved the extradition request for Mr Arapi.
Jago Russell, from Fair Trials International, which is backing him, said he was the victim of a "horrendous" miscarriage of justice, made possible by the European Arrest Warrant scheme.
"Fair Trial International's main concern about the European Arrest Warrant system is the lack of judicial discretion - the lack of an ability of a British court to say 'no it would be unjust to extradite somebody to another country' - and therefore to stop the extradition," he said.
"Before this system was introduced it was possible for the British government to... stop an extradition or for the British courts to do so.
"That's all gone now - the British courts in the vast majority of cases now simply have to rubberstamp requests for extradition from other European countries," Mr Russell said.
The BBC asked the Italian Ministry of Justice to comment on the case but it did not respond.
The UK Serious Organised Crime Agency (SOCA), which processes extradition requests, declined to discuss the case but pointed out that the European Arrest Warrant system was designed to "streamline" the process and provide "mutual recognition" of judicial decisions in the EU.
The Home Office has announced a review of extradition arrangements, but it is likely to take some months - and may not come in time to help Mr Arapi.
The High Court will hear an appeal against his extradition later in June.
His wife, Georgina, said she was worried that if the appeal failed and Mr Arapi was to be extradited, she would be unable to pay the mortgage, leaving her and their children - two daughters under eight and a son just a week old - homeless.
She said "common-sense" must prevail and urged the authorities to recognise that Edmond Arapi was innocent.
"He doesn't go out with his mates drinking, gambling," she said.
"He doesn't take drugs. He comes home every week with his wage and gives it me.
"That's what kind of person Ed is - that's my husband."