Abdelbasit Alhaj Alhassan Haj Hamad and Mohamed Makawi Ibrahim Mohamed escaped from prison in 2010 and are still on the run, U.S. officials said in a release. They were sentenced to death in 2009.
The U.S. government has offered $5 million rewards for information leading to their capture or death.
John Michael Granville, 33, who worked for the U.S. Agency for International Development, and Adbelrahman Abbas Rahama, a 40-year-old USAID employee serving as Granville's driver, were gunned down Jan. 1, 2008, as they left a New Year's Eve party in Khartoum. Granville, a career diplomat, was credited with an effort to supply solar-powered radios to people living in remote parts of Sudan so they could be informed about the impact of negotiations on Darfur and South Sudan. Abbas, a native of Juba, which is now the capital of South Sudan, had worked for USAID since 2004.
Three other men were involved in the killings and were convicted. Two escaped from a maximum-security prison in Khartoum, Sudan's capital, with Hamad and Mohamed, but one has been recaptured and the other killed.
A group apparently affiliated with al-Qaida post a video Dec. 28 purportedly showing the men's escape, the Sudan Tribune reported at the time.