Sudan has condemned an attack in which a US diplomat and his driver were shot dead in the Sudanese capital, Khartoum.
Mr Granville was shot five times while travelling in his car
Sudan's foreign ministry ruled out a terrorist attack, though a US official said it was too early to determine a motive for the shooting.
The diplomat, who has been named as John Granville, died of his wounds after his car was shot at during the early hours of Tuesday.
Mr Granville's Sudanese driver died instantly in the attack.
"On behalf of the Sudanese Foreign Ministry, we would like to express our deep regret and our condemnation of this incident," foreign ministry adviser Ali al-Sadiq told the BBC.
"We don't believe this incident has any relation whatsoever to any act of terrorism," he said.
However, a spokesman for the US embassy in Khartoum said it was "too early to tell" whether the attack was related to terrorism.
Mr al-Sadiq said investigations were continuing in collaboration with US security agencies.
"The main objective is to find the culprits, arrest them and bring them to justice so they get what they deserve for their crime," he said.
Mr Granville, 33, was an officer with the US Agency for International Development.
Sudan's interior ministry said his embassy vehicle was fired on by gunmen in another car as it drove through a residential area of western Khartoum.
It said Mr Granville was shot five times in the hand, shoulder and stomach.
The driver, identified as 40-year-old Abdel Rahman Abbas, was killed instantly, the ministry said.
The shooting happened the day after a joint African Union-United Nations force took over peacekeeping duties in Sudan's war-torn Darfur region.
Anti-Western and anti-US feelings are running high in Sudan, because of Western criticism of Khartoum's policies in Darfur, correspondents say.
But attacks on foreigners in Khartoum have been rare.