The four men said their confessions had been obtained through torture
A Sudanese court has upheld a death sentence against four Islamists who shot dead a US envoy on 1 January 2008.
John Granville, 33, and his Sudanese driver Abdelrahman Abbas Rahama were killed as they returned from a New Year's Eve party in Khartoum.
Mr Granville's mother had earlier asked for the death sentence to be passed.
Under Sudan's Islamic law, the family of a murder victim can either request the death penalty for those convicted, forgive them or ask for compensation.
A death sentence was originally passed in June but some members of Mr Abbas' family then pardoned the killers, reports the AFP news agency.
The four have always protested their innocence, saying their videotaped confessions were extracted under torture.
Mr Granville was shot five times while travelling in his car
After the sentence was read out, defendant Mohaned Osman shouted: "This sentence is not credible," and said the US had murdered Muslims, according to Reuters news agency.
In a letter read out to the Khartoum North court on Sunday, Mr Granville's mother formally demanded the death penalty in order to "safeguard the lives of others from those who killed her beloved son". There was no option of life imprisonment
The FBI had sent agents to help investigate the murder of Mr Granville, who worked for the US Agency for International Development.
The incident shocked many people, including the small Western community in Khartoum.
The Sudanese capital had previously been considered one of the safest in Africa.
The BBC's James Copnall in Khartoum says there have been some concerns that the incident could prove damaging for the already fragile relationship between Sudan and the US.
The Sudanese authorities condemned the attack immediately, and seem to have made resolving the case a priority, our reporter says.